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Biomedical subjects

S Hamilton

Publications and source records attributed to S Hamilton.

At least 55 records · Page 3Linked to original sources
PubMed1991

A safe new procedure for high-risk patients with symptomatic gallstones.

Cholecystectomy is associated with an appreciable mortality rate in elderly high-risk patients. Patients aged over 60 years with symptomatic gallstones, at high operative risk, underwent cholecystotomy under local anaesthesia through a 3-cm incision. Stones were removed and clearance was demonstrated endoscopically and by tube cholecystography. Catheter drainage was continued for 7 days until a further cholecystogram confirmed clearance. The procedure was attempted in 26 patients with concomitant cardiovascular, respiratory or malignant disease. Successful removal of all gallbladder stones was possible in 24 patients. Four patients had common bile duct stones demonstrated on cholecystography, all of which were successfully treated by endoscopic sphincterotomy. All patients are symptom-free at a mean follow-up of 36 weeks with no recurrent stones on ultrasonography.

Aged↗
PubMed1991

Spontaneous recovery of renal function after resection of contralateral hypernephroma.

We report a case of nonfunction of an anatomically normal kidney associated with a contralateral hypernephroma. X-ray and radionuclide imaging suggested a disturbance of the contralateral renal blood flow at the microvascular level. Normal function resumed after tumor resection. The implications for management are discussed.

Carcinoma, Renal Cell↗
PubMed1991

Prolonged travel time to neonatal intensive care unit does not affect content of parental visiting: a controlled prospective study.

Decreased local obstetric care appears to be increasing the rate of premature births to rural populations. With increased numbers of premature and complicated births in rural populations, understanding the impact of the Neonatal Intensive Care Unit (NICU) environment on the development of parent-child relationships becomes critical. NICU infants appear to be at increased risk for failure to thrive, child abuse, and neglect. Some reports suggest that the frequency of parental visits to the NICU can predict infants likely to be at risk. Because rural parents visiting infants hospitalized in urban centers are likely to visit less often, understanding this possible relationship is critical. In this controlled prospective study, three groups of parents were observed visiting their hospitalized infants: (1) those visiting "in house" while the mother was still hospitalized; (2) those whose visits required one hour or less in travel time; and (3) those whose visits required more than one hour in travel time. Results showed that travel time influenced the frequency of visits, with fewer visits from those living furthest from the NICU. However, those visiting from greater distances stayed with their infants longer so that there was no difference in the total visiting time over a two-week period. Direct observations of the visits by both mothers and fathers showed no differences in the content of parent-child interactions among groups. Thus, visit frequency alone must be viewed cautiously as a potential indicator of failure to bond with a hospitalized infant, especially in settings serving rural populations.

Adult↗
PubMed1990

p53 gene mutations occur in combination with 17p allelic deletions as late events in colorectal tumorigenesis.

Coordinate loss of one copy of the p53 gene and mutation of the remaining copy occur in colorectal carcinomas and in many other human malignancies. However, the prevalence of p53 gene mutations in carcinomas which maintain both parental copies of p53 has not previously been evaluated. Moreover, it is not known whether p53 gene mutations are limited to malignant tumors or whether they can also occur in benign neoplasms. To answer these questions, a total of 58 colorectal tumors have been examined; in each tumor, allelic losses were assessed using restriction fragment length polymorphisms and p53 gene mutations were assessed by sequencing cloned polymerase chain reaction products. The following conclusions emerged: (a) p53 gene mutations occurred but were relatively rare in adenomas, regardless of size and whether the adenomas were derived from patients with familial adenomatous polyposis; (b) In carcinomas as well as in adenomas, p53 gene mutations were infrequently observed in tumors which contain both copies of chromosome 17p (17% of 30 tumors), while tumors which lost one copy of chromosome 17p usually had a mutation in the remaining p53 allele (86% of 28 tumors); (c) p53 gene mutations were found at similar frequencies in primary tumor samples and in cell lines derived from tumors. These and other data suggest that the rate limiting step in p53 inactivation is point mutation and that once a mutation occurs, loss of the remaining wild-type allele rapidly follows. Both mutations and allelic losses generally occur near the transition from benign to malignant growth, and the p53 gene may play a causal role in this progression.

Adenoma↗
PubMed1990

The bistratenes: new cytotoxic marine macrolides which induce some properties indicative of differentiation in HL-60 cells.

The biological effects of cytotoxic macrolide polyethers, the bistratenes, isolated from the ascidian Lissoclinum bistratum, have been examined. Bistratene A was toxic to HL-60 human promyelocytic leukemia cells with an IC50 value of 424 nM. At lower concentrations (10-100 nM), bistratene A induced the incomplete differentiation of these cells along the monocyte/macrophage pathway. These effects were not due to inhibition of DNA synthesis. Bistratene B had similar effects to bistratene A. At micromolar concentrations these compounds enhance the phospholipid-dependent activity of type II protein kinase C from bovine spleen. The bistratenes provide new probes for studying the molecular mechanisms governing cell growth and differentiation.

Acetamides↗
PubMed1990

Biliary intervention via minicholecystostomy.

Minicholecystostomy was performed in 24 elderly patients, under local anaesthesia. All had symptomatic gallstones removed utilizing endoscopy and fluoroscopy. These procedures were well tolerated, with no significant complications, despite severe coexistent disease. One patient has had recurrent problems due to gallstones and one has died from disseminated malignancy. The remaining 22 are well and symptom-free. This combined surgical and radiological approach is a useful alternative procedure for patients with gallstones who are a poor risk for general anaesthesia.

Aged↗
PubMed1989

Two mutants of Dictyostelium discoideum that lack a sulfated carbohydrate antigenic determinant synthesize a truncated lipid-linked precursor of N-linked oligosaccharides.

Dictyostelium discoideum glycoproteins contain mannose-6-SO4 in highly immunogenic N-linked oligosaccharides. To more precisely define the structural requirements of the antigenic determinant, we have analyzed the oligosaccharides synthesized by two mutant strains (HL241 and HL243) that lack it. Both mutant strains synthesize N-linked oligosaccharides which are very similar to each other but are smaller and less charged than those derived from the wild-type. Both mutants contain substantial amounts of Man-6-SO4, and only a single residue of Man-6-P-OCH3 per chain, in contrast to the wild-type which may have 1 or 2 such residues. Neutral species are similar to the wild-type in that they can still be modified by the addition of residues of fucose and N-acetylglucosamine. Both mutant strains synthesize a truncated lipid-linked oligosaccharide, Man6GlcNAc2, with the most probable structure being: (sequence; see text) based on Jack bean alpha-mannosidase, alpha-1,2-specific mannosidase digestions and methylation analysis. The presence of this small oligosaccharide appears to result from the loss of the mannosyltransferase(s) needed to synthesize structures larger than Man6GlcNAc2 and not from the absence of dolichol phosphate or dolichol-P-mannose synthetase. These data along with the analysis of another mutant strain suggest that the expression of the antigenic determinant requires a specific arrangement of Man-6-SO4 on the alpha-1,6 branch of the oligosaccharide linked to the beta-mannose.

Carbohydrate Sequence↗
PubMed1989

Multiple and repetitive uses of the extended hamstring V-Y myocutaneous flap.

An extended hamstring V-Y myocutaneous advancement flap is described that may be used to cover unusually large defects in the ischial region. Technical points that allow a large amount of flap advancement are discussed. Because of its large size, the flap can be raised and used on repeated occasions to repair defects from recurrent ischial pressure sores. Two patients are presented in whom the same flap was used repeatedly on multiple occasions, demonstrating the potential for preservation of future options in such patients when this flap is used.

Humans↗
PubMed1989

Nipple reconstruction with the double-opposing-tab flap.

The double-opposing-tab flap, a new method of nipple reconstruction used in 50 patients to date, is described. This technique uses two dermal-fat flaps, each similar to those described by Hartrampf, but with tab extensions inspired by the skate flap of Little. The donor sites of the two flaps are closed like Burrough's triangles, bringing the flaps into opposition so that they support each other's projection. The tabs cover all the exposed fat on the nipple so that no skin graft is required on the nipple proper. The result is a nicely shaped nipple that can be designed directly over a scar, maintains a projection averaging 3.8 mm at 10 months, and is technically easy to construct.

Breast↗