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Biomedical subjects

R Sriram

Publications and source records attributed to R Sriram.

At least 19 recordsLinked to original sources
PubMed2002

An audit of urodynamic standardization in the West Midlands, UK.

OBJECTIVE: To report a follow-up postal survey to one conducted in 1998 assessing the feasibility of standardizing urodynamic practice in the West Midlands region. METHODS: From the initial survey there was interest in standardizing the practice of urodynamics and a few simple guidelines were proposed. The postal survey was repeated to identify any changes. The guidelines included zeroing the transducer to atmospheric pressure, a filling rate of 50 mL/min and using the International Continence Society (ICS) definition of detrusor instability, including numerical values and recording any contraction in the presence of urgency. A questionnaire, similar to the initial one, was circulated to all the clinicians who had participated in the initial study, distributed approximately 8 months after agreed guidelines were issued. Specific questions included details of the filling and voiding cystometrogram, and the basis of diagnosing detrusor instability. They were also asked to comment on whether they would still like the practice to be standardized. RESULTS: Only 17 of the 23 clinicians who participated in the initial study responded. For zeroing the transducer to atmospheric pressure, eight still zeroed to the patient. Only one unit had changed its practice by zeroing to atmospheric pressure. Varied rates of filling were still used and only eight participants used the ICS criteria to diagnose detrusor instability. Three of the 17 participants did not feel that standardization was achievable. CONCLUSIONS: Obviously there is some apathy amongst clinicians to move towards standardization. No significant changes had been made since standardization guidelines were issued. Although most preferred initially to standardize urodynamic practice, individuals do not seem to have been convinced that they need to change their method to achieve uniformity.

England↗
PubMed1999

Angioplasty and stenting of solitary supra-aortic artery and aortoplasty by kissing balloon technique.

A child presented with symptoms of compromise to cerebral blood flow and cardiac failure. On diagnostic angiography, he was found to have a discrete coarctation and related ostial stenosis of the left subclavian artery, which acted as the sole source of cerebral blood flow. The subclavian lesion was initially dilated with a 6 mm x 50 mm balloon. The discrete coarctation was then dilated with an 8 mm x 50 mm balloon. Since significant residual stenosis was present at the subclavian origin, it was stented with a 20 mm Palmaz-Schatz stent (Cordis Corporation, Miami Lakes, Florida). Since the coarcted segment required further dilatations, the kissing balloon technique was used, wherein the 6 mm balloon was placed extending from the left subclavian lesion distally to the related aortic lesion proximally, along with another 10 mm balloon in the aorta. The end result was acceptable and the patient's symptoms improved significantly after the procedure.

Angioplasty, Balloon↗
PubMed1997

Percutaneous Transvenous Mitral Commissurotomy Without Heparin.

Six-hundred twenty-nine patients with rheumatic mitral stenosis in normal sinus rhythm underwent percutaneous transvenous mitral commissurotomy (PTMC) by the standard Inoue balloon technique. All patients underwent transthoracic echocardiography, when necessary, transesophageal echocardiogram was done before PTMC to exclude left atrial clot. In all cases, the PTMC procedure was completed without administration of heparin. There was no incidence of embolism either in the immediate post-procedure period or at a median follow-up of 3 months. There were no femoral artery or venous complications in any of the cases. We conclude that the conventional use of heparin during PTMC may not be required in patients with sinus rhythm and no left atrial clot.

Journal Article↗
PubMed1993

A new expandable intracoronary tantalum (Strecker) stent: early experimental results and follow-up to twelve months.

A new radiopaque balloon expandable tantalum stent was tested in the coronary arteries of sheep. A total of 28 stents with a diameter of 2.0 to 3.8 mm were successfully deployed. The stent to coronary artery diameter ratio was 1.1-1.2:1. The animals were heparinized with 100 U/kg of heparin but did not receive antiplatelet drugs. Coronary angiography that was performed 10 minutes after stent implantation showed 100% patency with no side-branch occlusion. Four sheep died within 2 hours of stent implantation, and pathologic studies showed thrombosis of the smaller sized stents: 2 mm (n = 2), 2.8 mm (n = 1), and 3.2 mm (n = 1); three fourths of the sheep had two stents implanted. An oversized stent caused coronary rupture and cardiac tamponade in one other sheep. Follow-up study protocol included coronary angiography before animal sacrifice and pathologic studies within 48 hours (n = 11), 2 weeks (n = 1), 3 months (n = 2), 5 months (n = 1), 10 months (n = 7), and 12 months (n = 1). At 3 to 12 months of follow-up the coronary stent was completely covered with a layer of neointima, and there was no angiographic evidence of coronary stenosis and patent side branches. According to histologic examination, the neointima had nonuniform thickness (20 to 330 microns) and consisted of smooth muscle cells and some collagen. At 7 months of follow-up one of seven stents had angiographic (20%) and pathologic evidence of stenosis, which was secondary to thrombus. The tantalum device is easily deployed technically and notable for its excellent fluoroscopic visibility and flexibility. Thrombosis with a tantalum stent remains a problem, and therefore the larger diameter stents > or = 3.2 mm, antiplatelet drugs, and anticoagulation therapy are indicated for human studies. Implantation of multiple coronary stents increases the risk of stent thrombosis. The long-term, mild neointimal thickness and the patency of the stent and side branches are encouraging.

Animals↗
PubMed1993

Purification and biochemical characterization of gamma-glutamylcysteine synthetase from a human malignant astrocytoma cell line.

gamma-Glutamylcysteine synthetase (EC 6.3.2.2.) the key regulatory enzyme in glutathione biosynthesis was purified from a human malignant astrocytoma cell line using a combination of ammonium sulfate fractionation, DE-52 cellulose chromatography and ATP-agarose affinity chromatography. The purified protein had a specific activity of 1725 units/mg protein, which represented an 86-fold purification and a 22% yield. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed two major subunits with apparent molecular sizes of 72 kDa and 32 kDa. The Km values for L-glutamate and L-alpha-aminobutyrate were 0.03 mM and 0.14 mM respectively. These molecular and catalytic properties of gamma-glutamylcysteine synthetase from astrocytoma cell line are similar, but not identical to those purified from rat kidney.

Ammonium Sulfate↗
PubMed1992

Balloon coarctation angioplasty in adolescents and adults: early and intermediate results.

Twenty-three adolescent and adult patients with native coarctation of the aorta underwent balloon dilatation. Dissection of the aorta developed in one patient. Data were collected on the remaining 22 patients. They ranged in age from 15 to 55 years (mean 23 +/- 9.2 years). Invasive measurement of the peak systolic gradient (PSG) and biplane angiography were performed before and immediately after angioplasty and at follow-up 4 to 48 months (mean 15 months) later. PSG before dilatation was 37 to 100 mm Hg (mean 66.9 +/- 19.9 mm Hg) and decreased to 0 to 30 mm Hg (mean 9.1 +/- 11 mm Hg) immediately after dilatation (p less than 0.001). Restenosis occurred in two patients 6 months after dilatation, and one patient had an incomplete dilatation. These three patients underwent successful redilatation and remained improved 12 to 19 months later. There was no significant change in gradient at repeat catheterization in the remaining 20 patients. PSG was 0 to 20 mm Hg (mean 5.8 +/- 7.2 mm Hg). Angiography showed that a small aneurysm developed in one patient immediately after dilatation and in another 6 months later. Eleven patients were restudied more than once, and no change in gradient or size of the aneurysm was noted at mean follow-up 25 months after dilatation. This study demonstrated that balloon angioplasty is an effective method of treating adolescent and adult patient with native coarctation of the aorta. However, because of the uncertain natural history of aneurysm after dilatation, this procedure should be considered investigational until much longer follow-up times are available.

Adolescent↗
PubMed1991

Informed consent: a study of experiences and opinion of utilizers of health services from India.

One hundred and forty-eight subjects drawn from urban and rural settings who had been hospitalized for any medical problem within the previous three years were interviewed using a semi structured interview schedule to understand their opinion and experiences of informed consent. Sixty medical officers providing primary care in both urban and rural areas were concurrently interviewed to gather their opinion. Results revealed that respondents were dissatisfied with the information they had received about the different aspects of their illness. Both the doctors and the patients felt the need for providing adequate information to utilizers of health services. The two groups identified certain constraints, like illiteracy, in obtaining informed consent. Doctors compared to patients more often thought that illiterates could not understand the information. Patients more often felt that information about nature of investigations and about prognosis need not be routinely revealed.

Adolescent↗
PubMed1991

Characterization of cisplatin degradation as affected by pH and light.

The stability of cisplatin in 0.9% sodium chloride solution was studied. Cisplatin was reconstituted with sterile water for injection to achieve a concentration of approximately 1 mg/mL in 0.9% sodium chloride solution. The solutions were placed in flexible polyvinyl chloride containers, clear and amber glass flasks, and plastic syringes and stored at 22-25 degrees C in the dark or exposed to measured amounts of light and assayed periodically for up to 96 days. The initial pH of some of the solutions was adjusted. The stability of cisplatin in the solutions was determined by measuring the concentrations of cisplatin, trichloroammineplatinate(II) (TCAP), and trans-dichlorodiammineplatinum(II) (transplatin) with high-performance liquid chromatography and by measuring solution pH. The effect of adding ethylene oxide and other materials was also determined. TCAP was identified as the predominant degradation product of cisplatin in all the solutions. The rate of degradation was dependent on pH: In the dark, about 0.04% and 0.21% of the cisplatin degraded to TCAP per week at pH 4.3 and 6.3, respectively. The presence of ethylene oxide accelerated cisplatin degradation. Degradation also occurred during exposure to short-wavelength (350-490-nm) visible light. Storage in amber glass flasks offered more protection than storage in clear flasks. Isomerization of cisplatin to transplatin was not observed. The major degradation product of cisplatin was trichloroammineplatinate(II). Solution pH was the predominant factor affecting cisplatin stability.

Chromatography, High Pressure Liquid↗
PubMed1991

Mitral balloon valvotomy using the Inoue balloon technique for selected patients with severe pliable rheumatic mitral valve stenosis: immediate and short-term results.

We selected 40 patients with severe symptomatic rheumatic mitral stenosis for balloon valvotomy using the Inoue balloon technique. The patients' mean age was 31 +/- 14 years and there were 24 females and 16 males. The patients were selected according to the following echo/Doppler criteria; 1. Severe mitral stenosis, i. e. mitral valve area (MVA) less than 1.1 cm2; 2. pliable anterior mitral valve leaflet; 3. absence of calcification of the mitral commissures and 4. absence of significant subvalvular mitral valve disease (Block echo score less than 8). We failed to cross the mitral valve in three cases and repeat attempts in two patients with higher transeptal puncture was successful. Thirty-nine procedures were technically successful (98%). There were no complications. We used an Inoue balloon size 24-30 mm using echo/Doppler guided stepwise mitral dilatation. After mitral balloon valvotomy, the MVA increased from 0.8 +/- 0.2 to 1.7 +/- 0.5 cm2 (p less than 0.001). Five patients developed mild mitral regurgitation and in one patient the degree of mitral regurgitation increased from mild to moderate. The mean mitral valve area 48 hours after the procedure measured 1.9 +/- 0.4 cm2 (echo/Doppler); one patient (2.5%) had residual mitral stenosis (MVA less than 1.5 cm2). At six weeks follow-up study the mean mitral valve area was 1.9 +/- 0.5 cm2 (Echo/Doppler), with no restenosis. We conclude that in selected cases of severe pliable mitral stenosis, the Inoue balloon technique achieves a greater than 100% increase of the MVA, without inducing significant iatrogenic mitral regurgitation or residual stenosis.

Catheterization↗
PubMed1990

Regression of infundibular pulmonary stenosis after successful balloon pulmonary valvuloplasty in adults.

Between July 1985 and March 1988, 22 adult patients with congenital pulmonary stenosis underwent balloon pulmonary valvuloplasty. There were 10 males and 12 females aged 16-45 (average 25 +/- 9.9) years. All patients had additional mild to severe infundibular stenosis; 16 were restudied 6-36 (mean 12.6) months later by repeat catheterization. Student's t-test was used for comparison of data. Right ventricular (RV) systolic pressure before dilatation was 84-196 (mean 129 +/- 32.3) mm Hg, and the peak pulmonary gradient (PPG) was 60-176 (mean 111 +/- 33.2) mm Hg immediately after dilatation. The RV systolic pressure dropped to 32-140 (mean 59.2 +/- 27) (P less than 0.001); and PPG dropped to 10-113 (mean 37.8 +/- 26.4) (P less than 0.001), and the infundibular gradient ranged from 8 to 113 (mean 35.1 +/- 25.8) mm Hg. The infundibular diameter, before dilatation, ranged from 2 to 15 (mean 9.5 +/- 4) mm Hg. At repeat catheterization, the RV systolic pressure dropped further to 33-66 (mean 42.8 +/- 9.7) mm Hg and the PPG was reduced to 0-48 (mean 18.4 +/- 10.9) mm Hg (P less than 0.001). The infundibular gradient regressed to 0-34 (mean 15 +/- 8.8) mm Hg (P less than 0.001). The infundibular diameter increased to 8-25 (mean 15.8 +/- 5.4) (P less than 0.001). It is concluded that moderate to severe infundibular stenosis, in adults, can regress after successful pulmonary valvuloplasty.

Adult↗
PubMed1990

Percutaneous balloon pulmonary valvuloplasty in sickle cell anemia: a case report.

Percutaneous balloon pulmonary valvuloplasty was performed on a 19-year-old female who had moderate pulmonary valve stenosis with sickle cell anemia. The patient developed sickle cell crisis resulting in occipital infarction, but she made a good recovery. We describe this case and the methods of reducing the risk of sickle cell crisis.

Adult↗
PubMed1990

S1-nuclease enhancement of the ethidium bromide binding assay of drug-induced DNA interstrand crosslinking in human brain tumor cells.

A modification, using S1-nuclease, of a simple and sensitive fluorometric assay with ethidium bromide was developed for the measurement of cellular DNA interstrand crosslinking induced by bifunctional alkylators. Cells are lysed and treated with proteinase K and sodium dodecyl sulfate followed by extensive dialysis to yield intact high-molecular-weight DNA, free of contaminating proteins, on which the crosslink assay is then performed. The assay depends on the differential binding of ethidium bromide to single- and double-stranded DNA. Because of the higher ethidium bromide binding capacity of double-stranded DNA, the fluorescence retained after a heating/cooling cycle is directly proportional to the drug-induced cellular DNA interstrand crosslinking. We demonstrate that the sensitivity of this assay can be increased up to fourfold by including an S1-nuclease digestion step. This modified technique is simple and suited to the quantitation of low levels of DNA-interstrand crosslinking in cells.

Alkylating Agents↗
PubMed1986

Further evidence for the role of 26 kDa peptide as mosquito larvicidal principle of the crystalline delta endotoxin of Bacillus thuringiensis var Israelensis.

Separation of the toxic and non-toxic subunits of the crystals of B. thuringiensis var israelensis, in native gels has revealed that the toxic subunit contained predominantly 26 kDa peptide, while the non-toxic subunit was made up of 66 kDa and other larger molecular weight peptides. Tryptic digestion of the crystal proteins and their separation on a DEAE-cellulose column, resulted in the generation of a fraction with a 21 kDa peptide, exhibiting larvicidal and hemolytic activities and immunoreactive with the antiserum of 26 kDa peptide of the crystals. These results show that 26 kDa peptide is the active principle of the crystal.

Bacillus thuringiensis↗
PubMed1985

Identification of the peptides of the crystals of Bacillus thuringiensis var israelensis involved in the mosquito larvicidal activity.

Tryptic digestion of the proteins from the purified crystals of B.thuringiensis var israelensis resulted in the decline of high molecular weight peptides without the loss of mosquito larvicidal activity, measured after immobilization of the digests with DEAE- Sephadex A 50 beads. Amongst the peptides generated (less than 44 kDa), a 21 kDa peptide was immunoreactive to the crystal antiserum. Analysis of the peptides released from spores of the toxic (Cry+) and non-toxic (Cry-) strains has revealed a pattern in which only the 26kDa peptide was missing in the Cry-strain. Sporulation and crystal formation were dissociated by the addition of the antibiotic netropsin, which could also inhibit the crystal assembly, without considerable decrease of the larvicidal activity and retention of the 26kDa peptide. These results implicate the 26kDa peptide in the larvicidal action.

Bacillus thuringiensis↗
PubMed1984

Left ventricular false tendons: echocardiographic incidence in India and clinical importance.

In a prospective study of 1012 patients above the age of 12 years, we detected 4 (0.4%) cases of left ventricular false tendon (LVFT) by echocardiography. Two patients had significant heart disease and LVFT was perhaps a chance occurrence; two others had no significant heart disease and LVFT probably had a causal association with S3 gallop in one and systolic murmur in the other. Diagnosis of LVFT may help to explain cardiac findings of uncertain origin.

Adolescent↗
PubMed1979

Child abuse.

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Child Abuse↗