Matthew S Clifton

University of California, San Francisco, San Francisco, CA, United States

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Publications (18)56.19 Total impact

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    ABSTRACT: Enteritis caused by Clostridium difficile toxin (Tx) is a nosocomial disease of increasing clinical concern, but the local mediators of C. difficile TxA inflammation are unknown. The potent vasodilator calcitonin gene-related peptide mediates neurogenic inflammation via the calcitonin receptor-like receptor (CLR). Here we examined the ileum-specific effects of reducing CLR on TxA ileitis by local preinjection of double-stranded RNAs. Treatment with CLR dsRNA for 7 d decreased CLR immunoreactivity, whereas treatment with non-CLR dsRNA did not. Subsequent injection of TxA in the same location increased CLR in rats treated with non-CLR dsRNA but not in rats treated with CLR dsRNA, documenting that local injection of dsRNA is effective in preventing the increase in CLR immunoreactivity in response to local TxA. After non-CLR dsRNA pretreatment, TxA induced robust intestinal secretion, myeloperoxidase activity, and histopathologic indications of inflammation including epithelial damage, congestion, neutrophil infiltration, loss of mucin from goblet cells, and increase in mast cell numbers. After CLR dsRNA pretreatment, TxA-induced changes in intestinal secretion and histopathologic inflammation were improved, including normal mucin staining and fewer resident mast cells. Loss of CLR prevented TxA-mediated activation of NF-κB and concomitant increases in pERK1/2 and TNF-α mRNA. Locally produced CLR plays a proinflammatory role in TxA ileitis via MAPK signaling and TNF-α. The results reported here strongly suggest that a local injection of dsRNA targeting CLR could be an effective local therapeutic approach at the inflammation site in the treatment of a growing, clinically relevant hospital-acquired disease, C. difficile infection.
    Proceedings of the National Academy of Sciences 12/2012; · 9.81 Impact Factor
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    ABSTRACT: Urocortins (UCNs) and their receptors are potent immunoregulators in the gastrointestinal (GI) tract, where they can exert both pro- and anti-inflammatory effects. We examined the contribution of Ucn1 and its receptors to the pathogenesis, progression, and resolution of colitis. Trinitrobenzene sulfonic acid was used to induce colitis in rats. Ucn1 mRNA and immunoreactivity (IR) were ubiquitously expressed throughout the GI tract under basal conditions. During colitis, Ucn1 mRNA levels fell below basal levels on day 1 then increased again by day 6, in association with an increase in the number of Ucn1-IR inflammatory cells. Ucn1-IR cells were also numerous in proliferating granulation tissue. In contrast to Ucn1 expression, average phosphorylated ERK1/2 (pERK1/2) expression rose above controls levels on day 1 and was very low on day 6 of colitis. Knockdown of corticotropin-releasing factor 2 (CRF(2)) but not CRF(1) by RNA interference during colitis significantly decreased the macroscopic lateral spread of ulceration compared with uninjected controls or animals with CRF(1) knockdown. After knockdown of CRF(2), but not of CRF(1) during colitis, edema resolution assessed microscopically was slowed, and myeloperoxidase activity remained elevated even at day 6. Ucn1 and TNF-α mRNA peaked earlier, whereas pERK1/2 activation was attenuated after CRF(2) knockdown. Thus we conclude that local CRF(2) and pERK1/2 activation is pivotal for macroscopic spread of colitis and resolution of edema. Elimination of CRF(2), but not CRF(1), results in uncoordinated immune and pERK1/2 signaling responses.
    AJP Gastrointestinal and Liver Physiology 02/2011; 300(5):G884-94. · 3.65 Impact Factor
  • Gastroenterology 01/2010; 138(5). · 12.82 Impact Factor
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    ABSTRACT: To evaluate the ability of a tumor-head volume ratio to predict outcome and incidence of hydrops in fetuses with sacrococcygeal teratoma. Seventy-one sonograms were reviewed retrospectively from 28 fetuses with sacrococcygeal teratoma managed in our institution. Head volume (HV) and total tumor volume were calculated from sonograms. Amount of cystic tumor was estimated to determine solid tumor volume (STV) for the STV/HV ratio. Twenty percent of sonograms with STV/HV <1 and 97.3% with STV/HV >1 were associated with 1 or more abnormal sonographic signs (p = 0.000). Overall mortality was 11/27 (41%). There was no mortality in fetuses with a ratio of <1, while 11/18 (61%) of fetuses with ratio >1 died (p = 0.003). The STV/HV ratio may be used to identify fetuses with a high risk of a poor outcome due to high-output cardiac failure and hydrops, and may help guide management.
    Fetal Diagnosis and Therapy 09/2009; 26(2):75-80. · 1.90 Impact Factor
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    ABSTRACT: To determine the intra- and interobserver reproducibility of human amniotic fluid metabolite concentration measurements (including potential markers of fetal lung maturity) detectable by MR spectroscopy. (1)H high-resolution magic angle spinning (HR-MAS) spectroscopy was performed at 11.7 T on 23 third-trimester amniotic fluid samples. Samples were analyzed quantitatively using 3-(trimethylsilyl)propionic-2,2,3,3-d(4) acid (TSP) as a reference. Four observers independently quantified eight metabolite regions (TSP, lactate doublet and quartet, alanine, citrate, creatinine, choline, and glucose) twice from anonymized, randomized spectra using a semiautomated software program. Excellent inter- and intraobserver reproducibility was found for all metabolites. Intraclass correlation as a measure of interobserver agreement for the four readers ranged from 0.654 to 0.995. A high correlation of 0.973 was seen for choline in particular, a major component of surfactant. Pearson correlation as a measure of intraobserver reproducibility ranged from 0.478 to 0.999. Quantification of choline and other metabolite concentrations in amniotic fluid by high-resolution MR spectroscopy can be performed with high inter- and intraobserver reproducibility. Demonstration of reproducible metabolite concentration measurements is a critical first step in the search for biomarkers of fetal lung maturity.
    Journal of Magnetic Resonance Imaging 12/2008; 28(6):1540-5. · 2.57 Impact Factor
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    ABSTRACT: Vascular endothelial growth factor (VEGF) is required for blood vessel formation during lung growth and repair. Alteration of VEGF isoform expression has been demonstrated in response to fetal tracheal occlusion and in models of lung injury. The purpose of this study was to investigate VEGF expression during compensatory lung growth in the mouse. Under general anesthesia, adult mice underwent left thoracotomy with (n = 5) or without (sham, n = 5) pneumonectomy. The right lungs were harvested at 1, 3, and 7 d after the operation. Lung-to-body weight ratio as well as total DNA and protein content were measured. VEGF protein expression was analyzed by Western blot and ELISA. VEGF isoform expression was evaluated using semi-quantitative PCR followed by Imagequant optical densitometry. Values were compared by Student's t-test and ANOVA using Fisher's protected least significant difference post-hoc test where appropriate. Compensatory lung growth was observed as measured by increases in right lung-to-body weight ratio and in DNA and protein content. Total VEGF RNA and protein expression did not change after pneumonectomy. However, on post-operative day 1, there was a decrease in the relative percentage of VEGF188 mRNA (P < 0.01), and an increase in the relative percentage of VEGF164 mRNA (P = 0.05). At 3 d postpneumonectomy, low relative VEGF188 expression persisted (P < 0.05), VEGF164 expression normalized, and relative VEGF120 expression increased (P < 0.01). Isoform expression in the pneumonectomy animals was identical to sham animals by the seventh d. There were no differences observed in VEGF receptor expression. During compensatory lung growth, we have observed an early postoperative reversion of VEGF isoform expression to the pattern seen during fetal lung development and in lung injury models.
    Journal of Surgical Research 12/2008; 160(1):107-13. · 2.02 Impact Factor
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    ABSTRACT: Fetal urinary tract obstruction with oligohydramnios produces pulmonary hypoplasia and renal dysplasia. Decompression of the obstructed urinary tract may restore amniotic fluid and allow lung growth, but transabdominal catheter shunt decompression is often inadequate and does not allow for cycling of the bladder, while open procedures cause significant maternal morbidity. Disruption of the anatomic obstruction, usually posterior urethral valves in a male fetus, would be ideal but has proven technically difficult. Here we describe a new technique of percutaneous fetal cystoscopy and disruption of posterior urethral valves, and the case report of our first application of this technique. We pre-sent a case of a 17-week male fetus with posterior urethral valves which underwent fetal cystoscopy for mechanical disruption of posterior urethral valves. This minimally invasive approach to disruption of posterior urethral valves in a fetus is a novel method for decompressing the urinary tract. The technique offers a minimal degree of maternal morbidity and, if instituted early enough, can restore amniotic fluid volume, avert fatal pulmonary hypoplasia and may preserve renal function.
    Fetal Diagnosis and Therapy 02/2008; 23(2):89-94. · 1.90 Impact Factor
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    ABSTRACT: Calcitonin gene-related peptide (CGRP) mediates neurogenic inflammation and modulates intestinal motility. The CGRP receptor is a heterodimer of calcitonin receptor-like receptor (CLR) and receptor-associated modifying protein 1. We used RNA interference to elucidate the specific role of CLR in colonic motility and inflammation. Intramural injection of double-stranded RNA (dsRNA) against CLR (dsCLR) into the colonic wall at two sites caused the spatial and temporal downregulation of CLR in the colon within 1 day of dsRNA injection. Knockdown of CLR persisted for 7-9 days, and the effect of knockdown spread to approximately 2 cm proximal and distal to the injection sites, whereas control dsRNA injection did not affect CLR expression. Measurement of isometric contractions of isolated colonic muscle segments revealed that in control dsRNA-injected rats, CGRP abrogated contractions entirely and decreased resting muscular tone, whereas in dsCLR-injected rats, CGRP decreased muscle tone but slow-wave contractions of varying amplitude persisted. In trinitrobenzene sulfonic acid-induced colitis, rats with knockdown of CLR displayed a significantly greater degree of edema and necrosis than saline- or control dsRNA-injected rats. Levels of the proinflammatory cytokines TNF-alpha and IL-6 were markedly upregulated by trinitrobenzene sulfonic acid treatment. TNF-alpha mRNA levels were further increased in CLR knockdown rats, whereas levels of IL-6 were unaltered. Thus this study demonstrates that CLR is a functional receptor for CGRP.
    AJP Gastrointestinal and Liver Physiology 08/2007; 293(1):G36-44. · 3.65 Impact Factor
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    ABSTRACT: Surgical intervention that improves pancreatic ductal drainage is a reasonable treatment strategy for recurrent pancreatitis in children. This study was approved by the Committee on Human Research (San Francisco, CA). A retrospective chart review was performed on children aged 0 to 17 years given the International Classification of Diseases, Ninth Revision coding diagnosis of chronic pancreatitis who underwent surgical intervention from 1981 to 2005. From 1981 to 2005, 32 children were treated for the diagnosis of chronic pancreatitis. The etiologies were obstructive (n = 13), idiopathic (n = 10), hereditary (n = 6), medications (n = 2), and infection (n = 1). Fifteen patients underwent 17 operations for chronic pancreatitis, including Puestow (n = 9), cystenterostomy (n = 2), Whipple (n = 1), distal pancreatectomy (n = 1), Frey (n = 1), DuVal (n = 1), excision of enteric duplication cyst (n = 1), and pancreatic ductal dilation (n = 1). The mean age at presentation of patients undergoing surgery was 6.0 +/- 4.1 years (mean +/- SD). The mean time from presentation to operation was 3.3 +/- 3.3 years. There were no deaths after surgical intervention. Of 15 patients, 2 (13%) required rehospitalization within 90 days of surgery, one for bowel obstruction, the other for splenic infarction. The median length of stay postoperatively was 8 days (range, 5-66 days). Chronic pancreatitis in children differs markedly in etiology when compared with adults. In most cases seen in our institution, chronic pancreatitis resulted from ineffective ductal drainage. These disorders are amenable to surgical decompression, which, ultimately, can prevent disease recurrence.
    Journal of Pediatric Surgery 08/2007; 42(7):1203-7. · 1.38 Impact Factor
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    ABSTRACT: It is becoming increasingly evident that the urocortins (Ucns) and their receptors are involved in the initiation and development of inflammation in the gastrointestinal (GI) tract. There has not been a systematic study of the basal expression of Ucns or their receptors in the GI tract. Here, we examined basal expression of Ucn 2 and its high-affinity receptor, CRF-R2 in the rat GI tract. Ucn 2 mRNA was expressed throughout the small and large intestine. Surprisingly, CRF-R2 mRNA expression was detected in only a subset of GI regions that expressed Ucn 2. Immunohistochemical study showed that both Ucn 2 immuno-reactivity (Ucn 2-IR) and CRF-R2-IR were consistently seen in the neurons of the myenteric plexus and the nerve fibers innervating the circular muscle. By and large, Ucn 2-IR was detected in all layers, including the mucosal and the submucosal layers throughout the GI regions. In contrast, CRF-R2-IR was very low or undetectable in the mucosal layers of all regions examined. The role of Ucn 2 and CRF-R2 was then examined in a rat model of chemically-induced colitis. In the early phase of colitis, Ucn 2 mRNA levels peaked, whereas, in striking contrast, CRF-R2 mRNA expression decreased approximately 2.5-fold below control levels. At the peptide level, Ucn 2-IR was specifically induced in a large population of immune cells that infiltrated the lamina propria and submucosa of the distal colon, whereas CRFR2-IR was detected in only a small fraction of infiltrated immune cells. CRF-R2-IR was dramatically reduced in the neurons of the myenteric plexus. Thus, we show, for the first time, that in the acute phase of inflammation, Ucn 2 levels are increased whereas expression levels of its only identified receptor, CRF-R2, are decreased. This suggests that Ucn 2 exerts its effects only in part via CRF-R2.
    Peptides 08/2007; 28(7):1453-60. · 2.52 Impact Factor
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    ABSTRACT: The natural history of certain prenatally diagnosed masses is well known. Large thoracic mass lesions can evolve one of 2 ways, either to regress and cause minimal morbidity, or to progress and enlarge, often resulting in hydropic changes in the fetus. This nonimmune hydrops carries a dismal prognosis, with nearly all fetuses expiring before or shortly after birth. However, hydrops associated with fetal mass lesions can be halted and even reversed with fetal intervention and treatment of the underlying defect. We examined our patients with fetal mass lesions to evaluate survival after intervention. Institutional approval was obtained by the Committee on Human Research. A retrospective review was performed of 294 fetuses evaluated over 15 years with large mass lesions. All patients were evaluated for evidence of fetal hydrops using ultrasound criteria. Patients were divided according to type of intervention. Primary outcome measure was 30-day survival after birth. (1) Patients without fetal hydrops did not undergo fetal intervention and survived to 30 days after birth (167/172, 97%). (2) Patients with fetal mass lesions that developed hydrops fared poorly with no intervention (1/33 survival, 3%), whereas fetuses undergoing prenatal intervention fared much better (15/30 open, 50%; 3/10 percutaneous, 30%). (3) Four patients with hydropic congenital cystic adenomatoid malformation (n = 3) or pulmonary sequestration (n = 1) received steroids in preparation for surgery but underwent no intervention, and the patients survived the neonatal period. Fetuses with prenatal diagnoses of masses not associated with hydrops have excellent prognosis with survival higher than 95%. Nonimmune hydrops associated with prenatal diagnosis of a fetal mass is a devastating complication with less than 5% survival. Open resection of a mass causing hydrops resulted in 50% survival, with reversal of hydrops in a group with near-uniform fatality. Further investigation is warranted regarding the use of minimally invasive prenatal therapies including steroid administration for hydropic fetuses.
    Journal of Pediatric Surgery 02/2007; 42(1):117-23. · 1.38 Impact Factor
  • American Journal of Roentgenology 02/2007; 188(1):W82-5. · 2.90 Impact Factor
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    ABSTRACT: Foregut duplications are rare entities that include both esophageal and bronchogenic cysts. The diagnosis of foregut duplication cyst is made most often from an incidental finding on chest radiograph, or due to respiratory compromise due to mass effect or infection. Treatment consists of complete resection. Recurrences are associated with incomplete resection. Six cases of foregut duplication cysts are presented that were resected thoracoscopically. From May 1998 to April 2003, six patients underwent thoracoscopy for resection of foregut duplication cyst. One patient required conversion to open thoracotomy due to esophageal perforation. The distribution of cysts was 4 on the left and 2 on the right; all procedures were performed with three or four ports. Single lung ventilation was used in three patients. The masses were removed via a port site after intrathoracic decompression. Chest tubes were placed in all patients, and most were removed within 12 hours. Five of six cases underwent successful thoracoscopic resection. Pathology demonstrated esophageal duplication cyst in three patients and bronchogenic cyst in the other three patients. Average hospital stay was 5.5 days. Complications included aspiration pneumonia and chest tube dislodgment. There were no deaths, and no recurrences. Thoracoscopic resection is a safe and effective method of treating foregut duplications. Outcomes have been good with little short-term morbidity and no mortality. Morbidity and cosmesis are improved by avoiding thoracotomy. Thoracoscopic resection should be considered the first-line therapy for these benign masses.
    Journal of Laparoendoscopic & Advanced Surgical Techniques 11/2006; 16(5):526-9. · 1.07 Impact Factor
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    ABSTRACT: Amniocentesis is an invasive procedure with inherent risks. Magnetic resonance (MR) spectroscopy is a safe noninvasive way of measuring levels of choline-containing compounds (including surfactant) and other metabolites. The purpose of this study was to test the feasibility of assessing fetal lung maturity in vivo and ex vivo using MR spectroscopy to determine differences in amniotic fluid choline concentrations between the second and third trimesters. Magnetic resonance spectroscopy was performed on ex vivo samples of amniotic fluid from second- and third-trimester fetuses. In vivo MR spectroscopy was performed on amniotic fluid and fetal lungs in third-trimester fetuses. Spectral acquisition and analysis were performed by an attending radiologist in conjunction with an MR spectroscopist. Choline-containing compounds were observed from 3.20 to 3.25 ppm. Comparison of spectra from second- and third-trimester amniocentesis revealed a trend toward increased choline at later gestational ages. Spectra from amniotic fluid and lungs of a third-trimester fetus showed that choline can be detected in the in vivo setting. Magnetic resonance spectroscopy is a safe noninvasive procedure that enables measurement of choline-containing compounds in fetal lung and amniotic fluid. Magnetic resonance spectroscopy shows a trend toward an increased quantity of choline in third- vs second-trimester amniocentesis.
    Journal of Pediatric Surgery 05/2006; 41(4):768-73. · 1.38 Impact Factor
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    ABSTRACT: Familial choledochal cysts are extremely rare. High-resolution ultrasound now allows for the antenatal diagnosis of these anomalies. After delivery, elective surgical resection should be planned; however, increases in size, deterioration of liver function, and ascending cholangitis frequently force early intervention. We report an unusual occurrence of siblings with type I choledochal cysts and review the existing literature on cause, genetics, classification, diagnosis, and management of this disease.
    PEDIATRICS 04/2006; 117(3):e596-600. · 4.47 Impact Factor
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    ABSTRACT: The sequelae of congenital diaphragmatic hernia (CDH) continue well beyond the perinatal period. Up to 50% of these patients have subsequent recurrent herniation or small bowel obstruction (SBO). A recent trend has been toward the use of bioactive prosthetic materials. We reviewed different patch closure techniques used for CDH repair at our institution and their association with these sequelae. A retrospective review was performed of 152 records for patients with CDH. Newborns that underwent patch repair for CDH and survived for at least 30 days were included in the analysis. Primary outcomes evaluated were recurrent herniation and SBO. Two types of prostheses were examined, Gore-Tex, an artificial material, and Surgisis, a bioactive material. Twelve (44%) of 27 patients who had Surgisis repair had recurrent herniation. Seventeen (38%) of 45 patients who had a Gore-Tex repair had recurrent herniation. Two additional patients in each group presented with SBO. No significant difference in recurrent herniation rates was observed (P > .5). The time to recurrence was similar in both groups (log-rank, P = .75), with most recurrences (92% Surgisis, 76% Gore-Tex) occurring in the first year. The rates of recurrent herniation and SBO after neonatal prosthetic patch repair of CDH were similar regardless of the prosthetic material used (Surgisis or Gore-Tex).
    Journal of Pediatric Surgery 02/2006; 41(1):29-33; discussion 29-33. · 1.38 Impact Factor
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    ABSTRACT: The aim of this study was to determine if patients are in remission or weaning off medication after thymectomy for myasthenia gravis (MG) and to examine the thoracoscopic versus open approaches. A retrospective review of all patients who underwent thymectomy for MG at a tertiary referral center between 1992 and 2004 (N = 14). Six patients (42.9%) underwent thoracoscopic resection. Eight patients underwent open resection; 5 (35.7%) had median sternotomy and 3 (21.4%) by transcervical approaches. Follow-up was obtained in 12 (85.7%) of 14 patients by both chart review and telephone. The mean follow-up was 43.0 months (range, 4-111 months). Statistical significance was determined by Student's t test or Fisher's Exact Test. The thoracoscopic group had a mean operating time of 138.8 minutes compared with 139.8 minutes in the open group (P = .9). The thoracoscopic group had a mean estimated blood loss of 7.5 mL compared with 52.5 mL in the open group (P = .02). The mean length of stay for the thoracoscopic group was 1.5 days (range, 1-2 days) and was 10.6 days (range, 3-41 days) in the open group (P = .13). Three (60%) of 5 patients were entirely off medication in the thoracoscopic group at the time of follow-up compared with 3 (50%) of 6 patients in the open group (P = 1.0). In the thoracoscopic group, 5 (83.3%) of 6 were in class 1 to 3 of the DeFilippi classification (complete remission or improved with decreased medication requirements). One patient had no change in symptoms (class 4). In the open group, 5 (83.3%) of 6 were classified as DeFilippi 1 to 3 at the time of follow-up, and one patient had worsening symptoms (class 5). Both thoracoscopic and open approaches to thymectomy in patients with MG are effective, with more than 80% of patients in both groups in remission or with improvement at the time of follow-up. The thoracoscopic group has the added benefits of decreased estimated blood loss, decreased length of hospital stay, and improved cosmesis. We advocate the thoracoscopic approach for thymectomy in the treatment of juvenile MG.
    Journal of Pediatric Surgery 02/2006; 41(1):50-4; discussion 50-4. · 1.38 Impact Factor
  • American Journal of Obstetrics and Gynecology - AMER J OBSTET GYNECOL. 01/2004; 191(6).