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Biomedical subjects

S H Silverman

Publications and source records attributed to S H Silverman.

At least 37 records · Page 2Linked to original sources
PubMed1989

The use of carbon dioxide gas to displace flowing blood during angioscopy.

Carbon dioxide (CO2) gas is a safe and effective arterial contrast agent that images arteries by displacing blood. The use of CO2 gas to displace blood during angioscopy may improve intraoperative angioscopy and allow percutaneous angioscopy. To study this, 46 angioscopic evaluations in the femoral arteries of four dogs were done without inflow occlusion. The ability of CO2 gas to clear the flowing blood was compared to a high-pressure infusion of saline solution. Carbon dioxide gas successfully displaced flowing blood in 20 of 25 evaluations (80%) as compared to three of 21 evaluations (14%) with infusion of saline solution (p less than 0.0001). After the CO2 gas infusion was stopped, the image remained clear for 9 +/- 1 seconds. When saline was used, the image was clear only as long as the infusion was continued. The quality of clear images for the two media were similar through the eyepiece of the angioscope, but images observed through the motion picture camera had better contrast and depth of field in CO2 gas. The use of a CO2 gas infusion can clear the field of flowing blood without the risk of volume overloading and potentially allow performance of a successful percutaneous angioscopy.

Animals↗
PubMed1989

Lipid risk factors in patients requiring arterial reconstruction.

Progressive peripheral atherosclerosis commonly leads to failure of a bypass graft. Lowering blood cholesterol retards coronary atherosclerosis and similar treatment might limit peripheral atherosclerosis. To identify lipid risk factors for peripheral atherosclerosis, 144 patients with peripheral atherosclerosis (98 with severe disease and 46 with stable claudication) and 61 age-matched control subjects were studied. Fasting lipid (cholesterol and triglycerides) and lipoprotein (high-density lipoprotein [HDL], low-density lipoprotein [LDL], and very-low-density lipoprotein [VLDL] cholesterol [C]) levels were measured. The incidence of hypertension and diabetes mellitus, amount of previous tobacco use, and location and severity of the peripheral atherosclerosis were also determined. Patients with peripheral atherosclerosis had higher VLDL-C and lower HDL-C levels than controls had, but serum cholesterol and plasma LDL-C levels were similar. Patients with peripheral atherosclerosis also had a higher incidence of diabetes mellitus and hypertension. Predictors of peripheral atherosclerosis by regression analysis were diabetes mellitus, low HDL-C levels, and tobacco use, with diabetes mellitus being the strongest variable. Peripheral atherosclerosis below the inguinal ligament was strongly predicted by low HDL-C and increased VLDL-C levels but not by increased cholesterol or LDL-C levels. Thus lipid risk factors for peripheral atherosclerosis are different, and attempts at limiting late graft failure by lowering lipid levels should be directed toward these lipoproteins.

Arteriosclerosis↗
PubMed1988

Effects of blood flow on laser probe temperature in human arteries.

Laser recanalization using metal capped fibers occurs by thermal vaporization of occluding plaque. However, little is known about the effects of blood and flow on the temperature of the laser probe or the arterial wall during lasing. To study this, probe and arterial wall temperatures were measured while a metal capped fiber, activated by an argon laser, was held stationary in a stenotic human peripheral artery. Arteries were perfused with saline and blood, and flow was varied from 0 to 140 cc/min. Probe temperatures were significantly higher in blood than in saline. However, the increased probe temperature achieved in blood was not transferred to the arterial wall. Increasing flow decreased probe temperature in both media, but again arterial wall temperatures were minimally affected. Thus, the presence of blood and flow may significantly affect heat generation and heat transfer during arterial recanalization using metal capped fibers.

Arteriosclerosis↗
PubMed1988

Cyanide toxicity in burned patients.

The role of cyanide (CN) in smoke inhalation injury has been the subject of investigation for many years. Prospective evaluation of serum CN, thiocyanate (the primary metabolic product of CN), and carboxyhemoglobin (COHb) in patients suspected by history of having smoke inhalation injury was performed in 144 patients. Eight of 12 patients with "lethal" CN levels (greater than 1.0 mg/L) died. All had sublethal levels of COHb. A separate group of patients who were DOA following fatal burn injuries were also studied. Lethal CN levels were found in 12 of 14 victims with lethal COHb levels and in 14 of 20 victims with sublethal COHb levels. The results show that elevated CN levels are frequent in patients with smoke inhalation and suggest that cyanide toxicity is a contributor to severe inhalation injuries. In some cases, CN was the primary measured toxicant.

Acidosis↗
PubMed1988

Single dose, oral antibiotic cover for transurethral prostatectomy.

A double-blind, randomised, placebo-controlled study was carried out to determine the incidence and significance of bacteriuria in 110 patients undergoing transurethral resection of the prostate (TURP) and to assess the effect of a single pre-operative dose of Ciprofloxacin, a 4-quinolone antibiotic. Fifteen (68%) of the 22 patients in the placebo group with a positive post-operative urine culture subsequently developed a clinically apparent urinary tract infection (UTI) or received antibiotics in view of a positive urine culture. Adequate prostatic concentrations of Ciprofloxacin were achieved in all who received the drug. A significant reduction in the number of positive post-operative urine cultures and urinary tract infections requiring antibiotic therapy was achieved in this group. Six patients (5.5%) developed clinical evidence of septicaemia, 5 of whom were in the placebo group. No organisms resistant to Ciprofloxacin were encountered. Prior to surgery, 19% of all patients were found to have previously unsuspected bacteriuria. Ciprofloxacin tended to reduce the chances of this group developing a UTI or requiring antibiotics. Further, there was a highly significant reduction in post-operative infective complications in those with sterile urine at the time of resection who had received the drug. This study suggests that antibiotic cover for TURP is of clinical benefit. Ciprofloxacin may prove suited to this purpose, although further experience with the drug is still required.

Administration, Oral↗
PubMed1987

Peripheral nerve concentrations of glucose, fructose, sorbitol and myoinositol in diabetic and non-diabetic patients.

Glucose, fructose, sorbitol and myoinositol concentrations were measured in biopsies of peripheral nerve obtained at above-knee or below-knee amputation. In diabetic patients nerve glucose (median [range]) (5.09 [1.62-12.82] vs 3.12 [1.81-4.01]) p less than 0.001, fructose (0.245 [0.060-1.280] vs 0.150 [0.053-0.385]) p less than 0.05, and sorbitol (0.028 [0.012-0.496] vs 0.016 [0.007-0.059] p less than 0.02, mumol/g wet weight) were significantly higher than in non-diabetic patients. No significant difference was found in myoinositol concentration (1.95 [1.00-3.55] vs 2.09 [1.27-5.40] mumol/g wet weight). Concentrations differed markedly from previously reported values in human nerve obtained at post-mortem.

Adult↗
PubMed1986

The effect of peritoneal lavage with tetracycline solution on postoperative infection. A prospective, randomized, clinical trial.

A prospective randomized trial was performed to determine the value of tetracycline lavage in addition to systemic antibiotic prophylaxis in 159 patients undergoing elective and emergency intestinal operations. Tetracycline lavage was associated with a significant overall reduction in postoperative infection rates in 25 of 74 patients (34 percent) receiving saline lavage compared with 15 of 85 patients (18 percent) having tetracycline lavage (P less than 0.05). Tetracycline lavage was associated with a significant reduction in the counts of aerobic and anaerobic bacteria in the peritoneal fluid at the end of the operation (P less than 0.05 and P less than 0.01, respectively) and with a significant reduction of aerobes 24 hours postoperatively (P less than 0.02). Tetracycline lavage would appear to confer clinical benefit in preventing postoperative infection.

Adolescent↗
PubMed1986

What is the role of histidine in studies of faecal mutagenicity?

Mutagenicity testing can be used to assay faeces for genotoxic substances and the results are reported to correlate with population risk for colorectal cancer (Ehrich et al., 1979). It has been suggested that histidine in faeces may cause false positive results (Venitt and Bosworth, 1983). To determine the relationship between histidine and false positive mutagenicity assays aliquots of non-mutagenic faecal extract and saline were supplemented with histidine and subjected to the Ames Salmonella/mammalian microsome mutagenicity assay (Ames et al., 1975). Using high-pressure liquid chromatography the analytical recovery of histidine from water and faecal extract supplemented with histidine was equivalent (r = 0.998, p less than 0.001). Histidine was measured in faecal extracts (1 in 10 dilutions) from 35 volunteers, 10 patients with inflammatory bowel disease and 4 with rectal cancer. These extracts were also assayed for mutagens using the Salmonella/mammalian microsome mutagenicity assay. None of the faecal extracts gave mutagenicity ratios above 2. Faecal extracts from volunteers were free of detectable histidine. Although 9 of those from inflammatory bowel disease patients contained histidine (mean +/- SEM 255 +/- 34 mumoles l-1) as did 1 extract from a rectal cancer patient (50 mumoles l-1), none contained sufficient histidine to give a false positive Salmonella/mammalian microsome mutagenicity assay result (800 mumoles l-1 in test solution). Our results do not implicate histidine as a cause of error in faecal mutagenicity testing by the Salmonella/mammalian microsome mutagenicity assay.

Chromatography, High Pressure Liquid↗
PubMed1986

Pharmacokinetics of single dose intravenous ciprofloxacin in patients undergoing gastrointestinal surgery.

The pharmacokinetics of single dose intravenous ciprofloxacin in patients undergoing gastrointestinal surgery (100 mg, n = 8; 200 mg n = 18) have been studied. Following 100 mg therapeutic serum levels were maintained for approximately 40 min only and tissue concentrations were frequently less than 0.15 mg/kg. 200 mg maintained therapeutic serum levels for at least 150 min and produced mean concentrations in fat, muscle, peritoneum and gut wall of 1.04, 1.94, 1.59, and 3.39 mg/kg respectively. 200 mg iv ciprofloxacin would appear to provide adequate serum and tissue concentrations for at least 150 min.

Abdominal Muscles↗
PubMed1986

Long-term management of patients who have had urinary diversions into colon.

Thirty-four patients with urinary-colonic diversions have been followed up for 13 to 41 years (mean 20.3). The commonest long-term complication was hyperchloraemic acidosis (50%). The most serious was neoplasm at the anastomotic site: benign lesions occurred in three patients and carcinomas in two (15%). Staining for sialomucins in colonic biopsies adjacent to the anastomoses was positive in 17 of 19 patients. It has been suggested that this represents a pre-malignant change. Analysis of faecal flora in 17 diverted patients and 27 controls revealed a significant difference in the carriage rate and viable count of Peptostreptococcus species. This finding has not been reported previously and the species could have a role in the aetiology of the neoplasms.

Colon↗
PubMed1986

The importance of laparotomy in the diagnosis and management of intestinal bleeding of obscure origin.

Thirty-seven patients who had had either a colonoscopy or a selective mesenteric angiogram while being investigated for severe or persistent gastrointestinal bleeding of obscure origin were reviewed. Failure to make a prompt diagnosis was partly responsible for the 16% hospital mortality in the series. Colonoscopy was diagnostic on 6 out of 38 examinations but detected 43% of lesions in the colon. Angiography achieved only 3 diagnoses in 17 examinations. Fourteen patients had an exploratory laparotomy which was diagnostic in 9. We believe that early laparotomy still has an important place in the diagnosis and treatment of intestinal bleeding of obscure origin.

Adult↗
PubMed1985

In vivo evidence that bacteria in urinary tract infection grow under iron-restricted conditions.

The outer membrane protein composition of bacteria isolated directly and without subculturing from the urine of two patients with urinary tract infections was investigated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The results indicated that the bacteria grew under iron-restricted conditions, as revealed by the expression of several high-molecular-weight outer membrane proteins which could also be observed when the same isolates were grown under iron-depleted conditions in laboratory media. The antigenicity of outer membrane components of the bacteria isolated was studied by immunoblotting with serum samples from the patients. The results indicated that the sera from the patients contained antibodies against major outer membrane components of the bacteria present in the urine, including the iron-regulated membrane proteins.

Aged↗
PubMed1985

Peroperative detection of patients with rectal cancer at high risk of local recurrence.

Identification at the time of surgery of patients with rectal carcinoma at high risk of local recurrence may allow a more rational decision to be made regarding the operative procedure to be performed. We have examined tumour bed biopsies and lymph nodes peroperatively using imprint cytology in 20 consecutive patients undergoing radical surgery for rectal carcinoma. The results were checked by subsequent paraffin section histology. We were unable to find lymph nodes in 6 cases (30%) peroperatively. Cytological and histological reporting of the tumour bed biopsies and lymph nodes concurred in 91% and 88% of specimens respectively. Peroperative cytology can differentiate between malignant and benign fixation of rectal tumours, can differentiate between hyperplastic and malignant lymph nodes and may be of value in identifying patients with rectal cancer at high risk of local recurrence.

Adult↗