P.T. Ramesh’s scientific contributions

The present study is focused to express the recombinant Leptospira surface adhesion-44 (rLsa44) protein of pathogenic Leptospira interrogans serovar Pomona in Escherichia coli and its diagnostic application in the latex agglutination test (LAT) system to detect anti-leptospiral antibodies in the bovine sera. The Lsa44 protein-coding gene sequences were amplified, the purified amplicon was initially cloned into the pGEM-T Easy vector, and subsequently to the pETite vector for the expression of rLsa44 in Escherichia coli. After induction with 1 mM isopropyl-β-D-thiogalactoside (IPTG), the expressed recombinant protein with a molecular weight of ~42 kDa was purified by the Ni-NTA affinity chromatography, characterized by SDS-PAGE and confirmed by Western blot using Leptospira specific sera. The sensitized latex beads (0.8 µm) coated with rLsa44 protein were prepared and assessed for their suitability as a diagnostic antigen in the LAT. Ten microliters of sensitized beads were used with test serum for agglutination, the results were recorded for 3 min and positive results were rated as +++, ++, +, if the clumps appeared after 1, 2, and 3 min, respectively. The rLsa44-LAT was evaluated for detection of anti-leptospiral antibodies using known Microscopic Agglutination Test (MAT) with positive (n = 74) and negative (n = 91) samples from apparently healthy animals, which revealed the relative diagnostic sensitivity (DSn) of 88% and specificity (DSp) of 84%. Furthermore, on the evaluation of standardized rLsa44-LAT using MAT-tested sera (positive-62 and negative-64) from cattle associated with a history of reproductive disorder, a DSn of 94% and DSp of 91% were observed. The developed rLsa44-LAT is a simple and rapid test that can be applied as a diagnostic tool at the field level as an on-site test after its extensive evaluation. This first study describing the expressed rLsa44 protein in Escherichia coli and used as a diagnostic antigen in LAT for the detection of anti-leptospiral antibodies in the sera of bovine as a preliminary screening test for leptospirosis.

The present study was undertaken to evaluate the effect of carvedilol and hawthorn extract in managing dilated cardiomyopathy (DCM) to limit the treatment cost and improve the quality of pet life. Total 165 dogs were subjected to detailed clinical and physical examination, electrocardiography and echocardiography. Out of 165 dogs, 61(36.96%) were diagnosed as DCM, out of which 30 were allocated randomly to three treatment groups comprising ten dogs in each group. Group-I dogs were treated with pimobendan, digoxin, enalapril and furosemide. In Group-II and III, pimobendan was replaced with carvedilol and hawthorn extract, respectively. Dogs with ventricular arrhythmias (Ventricular Premature Complexes, Ventricular fibrillation) were excluded from the treatment groups as digoxin is contraindicated in ventricular arrhythmias. A noticeable improvement in clinical signs, thoracic radiographic findings, left ventricular dimensions and left ventricular contractility indices was observed in the three treatment groups after 28 days of treatment when compared to the pre-treatment values. The drug's therapeutic efficacy was evaluated based on comparative assessment of post treatment left ventricular contractility indices (fractional shortening and ejection fraction). Group I had longer survival time with mean of 375 ± 14.25 days followed by Group III (264.67 ± 41.22 days) and Group II (214.57 ± 31.32 days) dogs.

Background: The measurement of tricuspid regurgitant velocity is the commonly used non-invasive method for the diagnosis of pulmonary hypertension in dogs. It is anticipated that M-mode echocardiographic measurement of right pulmonary artery distensibility (RPAD) index is simple and provides accurate means for the diagnosis of pulmonary arterial hypertension when tricuspid regurgitant velocity is absent. Hence this study was undertaken to evaluate the importance of RPAD index in the diagnosis and management of pulmonary arterial hypertension secondary to dilated cardiomyopathy. Methods: In the present study, a total of 165 dogs were subjected to echocardiography for diagnosis of pulmonary hypertension secondary to dilated cardiomyopathy. The maximum and minimum internal diameter of the right pulmonary artery during systole and diastole were quantified respectively to determine the right pulmonary artery distensibility (RPAD) index in right parasternal short axis M-mode echocardiogram. The M-mode morphology of right pulmonary artery (anterior dicrotic notch) also recorded. Result: Out of 165 dogs ten dogs had pulmonary arterial hypertension with dilated cardiomyopathy. Dogs with pulmonary hypertension showed a significant decrease in the mean right pulmonary artery distensibility index values and Acceleration time/Ejection time (AT/ET) ratio, while the mean tricuspid regurgitant systolic pressure gradient (TRPG) were significantly elevated when compared to the respective control group. The significant difference was observed in the mean values of tricuspid regurgitant systolic pressure gradient and RPAD index before and after the treatment.

A study was undertaken to compare the serum mineral profile in Holstein Friesian crossbred cows with low solids-not-fat (SNF) syndrome and normal SNF content during 4 th and 8 th week of 3 rd and 5 th lactations. A total of 24 cows were selected for the present study and based on the SNF content in their milk, the animals were divided into four groups, viz., Group I (> 8.5% SNF milk in 3 rd lactation), Group II (< 8.5% SNF milk in 3 rd lactation), Group III (>8.5% SNF milk in 5 th lactation) and Group IV (< 8.5% SNF milk in 5 th lactation) with six animals in each group. The blood samples collected at 4 th and 8 th weeks of lactation from all the selected animals were processed and serum samples were stored at-20°C till completion of the study. Stored serum samples were later utilized for determination of serum calcium, phosphorus, sodium, potassium, and magnesium with the help of autoanalyzer using specific reagent kits. Serum phosphorus and sodium levels were significantly (p<0.05) higher, and the serum potassium levels were significantly (p<0.05) lower in normal (>8.5%) SNF content cows compared to low SNF (<8.5%) syndrome cows at 4 th and 8 th weeks of 3 rd and 5 th lactations. However, the serum calcium and magnesium levels did not differ significantly between the groups. It was concluded that the significantly lower levels of serum sodium and phosphorous in cows with low SNF could be one of the contributing factors for the low SNF content.

Screening of antibiotic residues in cattle milk with emphasis on withholding time