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Biomedical subjects

H Chander

Publications and source records attributed to H Chander.

16 recordsLinked to original sources
PubMed1998

Aortic valve replacement with biological substitute.

In the quest for an ideal aortic valve substitute, homografts and autografts are well-established options. We reviewed our results with homografts and autografts for aortic valve replacement during the last 5 years. From March 1992 through July 1997, 189 patients (138 male and 51 female), age 8 months to 68 years (mean 31.0+/-4.2 years), underwent aortic valve replacement with a human biological substitute. Of these, 93 patients received a cryopreserved or antibiotic-preserved aortic/pulmonary homograft, whereas 96 patients underwent a Ross procedure. Etiology was rheumatic in 143 (75.6%) patients, bicuspid aortic valve in 40 (21.2%), Marfan's disease in 5 (2.6%), and myxomatous aortitis in 1 (0.5%). Among the homograft group, a scalloped subcoronary implantation technique was used in 54 patients, whereas 32 patients underwent root replacement. Five patients required aortic root and ascending aortia replacement for annuloaortic ectasia. In all patients undergoing the Ross procedure, a root replacement technique was used. Operative mortality was 7.4% (14 patients). Late mortality was 5.3% (10 patients). Follow-up ranged from 1 to 46 months postoperatively. In patients with homograft aortic valve replacement, 76 patients (91.5%) had trivial to mild aortic regurgitation, while 7 patients (8.4%) had important aortic regurgitation. In patients with the Ross procedure, 78 patients (89.6%) had trivial to mild regurgitation. Moderate to severe aortic regurgitation was present in 9 patients (10.3%), all of whom had rheumatic heart disease and were young (< 30 years at surgery). We conclude that homografts and autografts provide an excellent substitute for the diseased aortic valve. Young age (< 30 years) with rheumatic etiology is a major risk factor for early progressive aortic regurgitation in patients undergoing the Ross procedure.

Adult↗
PubMed1998

Experience with homograft mitral valve replacement.

BACKGROUND AND AIMS OF THE STUDY: Homograft mitral valve replacement may offer a superior alternative to replacement with a prosthetic valve. The authors' early experience with this technique is reported. METHODS: Between May 1994 and May 1995, 24 patients (19 males, five females; age range 17 to 49 years) underwent homograft mitral valve replacement (HMVR) at the authors' institution. The etiology was rheumatic in all patients; 22 had severe calcific mitral stenosis (MS) and two had combined MS and severe mitral regurgitation (MR). RESULTS: There were three early deaths (12%) and two late deaths (8%). In three patients the homograft had to be explanted due to severe MR at six weeks, 10 weeks and 12 months, respectively. Mean follow up was 18 months (range: 12 to 25 months). Postoperative echocardiography showed trivial or mild MR in 12 patients and moderate MR in four. Mitral stenosis was absent in all patients (mean mitral valve area 2.5 cm2). Sixteen patients showed satisfactory homograft valve function at follow up. The valve explanted after six weeks showed normal cusp architecture, endothelial growth and incorporation of the pericardial strip and complete healing of the papillary muscle junction. Magnetic resonance imaging in 12 patients showed normal appearance and function of the homografts. CONCLUSIONS: The authors' experience suggests that homograft mitral valve replacement can be performed with good early results.

Adolescent↗
PubMed1995

Pulmonary autograft aortic valve replacement. Early experience with the Ross procedure.

Aortic valve replacement with a pulmonary autograft was performed in 24 patients between October 1993 and October 1994, at the All India Institute of Medical Sciences, New Delhi. There were 20 (83.3%) males and 4 (16.7%) females. Their ages ranged from 10 to 56 years (mean, 21.46 +/- 11.45 years). Associated procedures included 10 mitral valve procedures (4 open commissurotomies, 5 mitral valve repairs, and 1 homograft mitral valve replacement) and 1 tricuspid valve repair. There were 4 (16.7%) early deaths, 3 of which were due to bleeding or its sequelae and 1 due to septicemia. There were no late deaths. Follow-up ranged from 1 to 13 months (mean, 198.3 +/- 111.1 days). Nineteen (95%) patients are in New York Heart Association functional class I, and 1 patient (5%) is in class II, due to poor left ventricular function. Only 1 patient showed grade 2/4 aortic regurgitation on follow-up examinations, and none has shown progression of aortic regurgitation. Our early results with the pulmonary autograft are encouraging; however, long-term evaluation is needed.

Adolescent↗
PubMed1988

Amine production by Streptococcus lactis under different growth conditions.

The highest amount of histamine, tyramine and tryptamine were produced by S. lactis at 30 degrees C in 24 h at pH = 5.0. Maximum amount of different amines was noted in a growth medium lacking NaCl. After addition of NaCl even at 0.5% concentration, slight inhibitory effect on the synthesis of these amines was obtained.

Biogenic Monoamines↗
PubMed1987

Changes in enterococcal population during storage of reconstituted infant food.

A six-fold increase in the enterococcal population was observed in reconstituted infant food samples after storage for 2 h at 37 degrees C. The increase in enterococcal counts at 40 degrees C and 45 degrees C was approximately five-fold during the same period. However, the corresponding total viable counts increased by twelve fold at these temperatures after 2 h. After 12 h, the enterococcal and total viable counts increased to 39 x 10(4) and 36 X 10(7) colony forming units per ml, at 37 degrees C respectively. A similar pattern in enterococcal and total bacterial count was observed at 40 degrees and 45 degrees C. TNase was detected in reconstituted infant food samples held at 37 degrees, 40 degrees and 45 degrees C, after 12 h, while pH values declined to 5.0, 5.1 and 5.2, respectively at the above temperatures. From TNase positive samples, an isolate S. faecium IF-100 capable to produce TNase was recovered. Storage of reconstituted infant food samples in the refrigerator (5 degrees C) resulted in a gradual increase in enterococcal population which reached 39 X 10(3) c.f.u. per ml after 12 days. However, TNase was not detected in any of these samples.

Food Handling↗
PubMed1986

Enterocin typing of enterococci isolated from dried infant foods.

One hundred and fifty enterococcal isolates recovered from 16 market samples of infant foods and 35 from other sources were characterized and subjected to enterocin typing with 18 indicator strains. Among 150 enterococcal isolates, 114 (76%) were able to be typed by the indicator strains. Although 24 enterocin patterns were observed with these enterococci, the most prevalent types were X-9, 224, and 65-603. Occurrence of pattern X-9 either singly or in combination with many other types was most frequent. Many of the enterocin patterns in enterococcal isolates were recovered from samples of dairy water supply and hand washings of personnel working in a dairy plant that manufactured infant food; this suggests the possibility of these as sources of contamination. Enterocin typing of enterococci could prove useful in epidemiological studies.

Animals↗
PubMed1975

Role of amino acids on the growth and lipase production of Streptococcus faecalis.

A study was conducted on the requirement of amino acids for the growth of S. faecalis and its lipase production. Arginine, glutamic acid, histidine, leucine, isoleucine, methionine, threonine, tryptophane and valine were found to be essential, with alanine, glycine, lysine and serine as stimulatory and aspartic acid, cystine, phenylalanine, proline and tyrosine as non-essential for both growth and lipase synthesis.

Amino Acids↗
PubMedDate not supplied

Surgery for aortic valve endocarditis.

From March 1994 to March 1997, 36 patients with aortic valve endocarditis were managed surgically. Of these, 30 patients had native valve endocarditis and six had prosthetic valve endocarditis. In patients with native valve endocarditis, surgical procedures included aortic valve repair (n=6), homograft aortic valve replacement (n=9), Ross procedure (n=5) and prosthetic aortic valve replacement (n=10). There were three early and two late deaths in this group. In patients with prosthetic valve endocarditis, aortic valve replacement with a homograft was performed in all. Active infection and prosthetic valve endocarditis were the most important predictors of early mortality. The availability of a homograft valve provides an alternative to prosthetic valve replacement in patients with aortic valve endocarditis.

Adolescent↗