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Biomedical subjects

R A Malt

Publications and source records attributed to R A Malt.

At least 55 records · Page 3Linked to original sources
PubMed1985

Chemoprevention and chemotherapy by inhibition of ornithine decarboxylase activity and polyamine synthesis: colonic, pancreatic, mammary, and renal carcinomas.

Specific, irreversible, inhibition of ODC activity with DFMO and resultant low levels of intracellular polyamines markedly suppress the induction of experimental colonic and mammary cancers and hold promise for augmenting the multidrug chemotherapy of established colonic, pancreatic, renal and mammary cancers without increasing systemic toxicity.

Animals↗
PubMed1985

Tube gastrostomy. Techniques and complications.

For prolonged gastrointestinal decompression or enteral nutrition, gastrostomies are preferable to nasogastric tubes. To assess the safety of tube gastrostomy, the authors reviewed 424 gastrostomies systematically selected from a total of 3,359 done from 1975 through 1980. Feeding gastrostomies composed 22% of the total; the remaining 78% were done for decompression. Complications were rare (6.6% major, 6.6% minor) and were not influenced by patients' age. Perioperative steroid therapy promoted laparotomy wound infections. External and internal leakage of stomach contents, as well as bleeding from the gastrostomy site, were independent of the method of gastrostomy and the type of catheter used. Feeding gastrostomies were more likely to leak internally than were decompression gastrostomies. Unless the gastrostomy site was sutured to the anterior abdominal wall, there was a 7% incidence of extravasation of stomach contents into the peritoneal cavity after removal of the tube. The low complication rate justifies use of gastrostomies as an alternative to prolonged nasogastric intubation. Problems are minimized by employing the Stamm technique with a straight catheter and anterior gastropexy.

Adolescent↗
PubMed1985

Prognostic factors in survival after portasystemic shunts. Multivariate analysis.

Multivariate analyses correlated short-term survival and long-term survival with clinical data from 141 patients with portasystemic shunts for bleeding esophageal varices over the 8 years from 1974 through 1981. By logistic regression analysis, the elements with independent prognostic significance for operative death were an emergency operation, serum albumin and bilirubin levels, age, and sex. A cutpoint probability value of 0.75 marked the single level above which 84% of patients could be expected to survive, but below which 77% are likely to die. By a Cox regression model, elements with independent prognostic significance were identical. Male sex (p = 0.02) and prolonged partial thromboplastin time (p = 0.04) indicated a poor prognosis after an emergency operation; after an elective operation only the serum albumin level was prognostic (p = 0.02). Normal blood clotting is the major determinant of survival after an emergency shunt, and the serum albumin level chiefly determines survival after elective portasystemic decompression.

Adult↗
PubMed1985

Intestinal resection in the neonatal rat: stimulus for precocious intestinal maturation.

To investigate whether intestinal resection accelerates mucosal maturation in suckling rats, macromolecular absorption, sucrase and lactase activity, RNA/DNA ratios, and intestinal morphology were determined 5 days after partial small intestinal resection or intestinal transection in 15-day-old rats. Villous height and crypt depth, lactase and sucrase activity, and RNA/DNA ratios were significantly increased in remaining intestine in animals that underwent surgery. These animals, together with normal control animals, were also gavaged with 100 mg bovine serum albumin, and serum levels were determined after 2.5 h. Mean serum levels of bovine serum albumin were 0.135 +/- 0.034 micrograms/ml/cm of residual intestine after transsection, 0.257 +/- 0.078 micrograms/ml/cm after resection, and 0.404 +/- 0.030 micrograms/ml/cm in controls. These studies demonstrate that intestinal resection during the suckling period of the infant rat results in several morphologic and physiologic changes that resemble precocious maturation of the small intestine.

Animals↗
PubMed1985

Implantable device for drug delivery and blood sampling in the rat.

An implantable drug-delivery and venous sampling device is described that is constructed from a polyvinyl chloride catheter and a rubber intravenous catheter plug coated with Silastic. The implant was used for repeated venous sampling and for both administration of parenteral solutions and injections into the right colon of the rat for periods to 1 mo.

Animals↗
PubMed1985

Effect of luminal contents on postresectional longitudinal and mucosal growth in the ileum of suckling rats.

Effects of luminal contents on adaptive growth of the ileum in the neonatal small bowel of rats were examined after resection of the proximal small bowel and after removal of the ileum from the enteric stream. Four weeks after resection of the proximal 60% of the small bowel in 10-day-old rats, the distal 40% of the small bowel elongated by 281%. This distal segment also elongated by 265% after intestinal transection (p greater than 0.05), but by only 191% when it was bypassed (bypass versus resection or transection, p less than 0.001). After resection the distal villi were 81% taller, but after transection they were only 19% taller (p less than 0.001 versus resection); after bypass they did not grow (p less than 0.001 versus resection or transection). The distal crypts were 404% deeper after resection, 331% deeper after transection (p less than 0.05), and 291% deeper after bypass (p less than 0.001 versus resection, p greater than 0.05 versus transection). The DNA content was 517% greater after resection, 364% greater after transection (p less than 0.001), and 73% greater after bypass (p less than 0.001 versus transection or resection). Maximal elongation of the small bowel occurs in the presence of luminal nutrition. Increasing luminal nutrition is associated with increasing mucosal hyperplasia.

Adaptation, Physiological↗
PubMed1985

Potentiation of 1,2-dimethylhydrazine-induced anal carcinoma by epidermal growth factor in mice.

Because epidermal growth factor (EGF) can modify cell proliferation in the gastrointestinal tract, effects of EGF were studied on the development of colonic, rectal, and anal neoplasms in male mice treated with 1,2-dimethylhydrazine (DMH) (20 mg/kg/wk for 20 weeks). DMH treatment caused a 13% increase in colonic RNA content, a 16% increase in DNA content, and 28% greater crypt depth. EGF (5 micrograms on alternate days during weeks 20 to 22) administered to DMH-treated mice produced no additional changes in colonic mucosa. At 30 weeks colorectal tumors were present in 13 of 20 mice treated with DMH (mean number of tumors per mouse 2.3 +/- 0.5) and 18 of 24 mice (mean 2.6 +/- 0.7) treated with DMH and EGF. Anal tumors were present in two of 20 DMH-treated mice (mean 0.1 +/- 0.07) but in eight of 24 DMH-EGF-treated mice (mean 0.33 +/- 0.1) (X2 = 4.84; p less than 0.05 for prevalence). Although EGF in this dose has no effect on the frequency of colorectal adenocarcinomas, the frequency of anal squamous cell carcinomas is increased more than three fold.

1,2-Dimethylhydrazine↗
PubMed1985

Acute colitis produced by chemotactic peptides in rats and mice.

Colonic inflammation was produced in rats and mice by peptides chemotactic for polymorphonuclear leukocytes. Instillation of formylmethionyl-leucyl-phenylalanine (FMLP) and formylnorleucyl-leucyl-phenylalanine (FNLP) into isolated segments of rat colon caused marked mucosal edema and polymorphonuclear leukocyte infiltration within 2 hours. Higher concentrations of FNLP caused ulceration and necrosis as well. Formylmethionine (FMet), a compound with less chemotactic activity, caused much less inflammation. In mice, rectal instillation of FNLP caused dose-dependent acute mucosal inflammation which persisted for longer than 12 hours. Twice-weekly rectal instillation of FNLP provided a model of colitis based on neutrophil chemotaxis.

Acute Disease↗
PubMed1984

Eclectic drainage of subphrenic abscesses.

In 196 cases of subphrenic abscess from 1964 through 1979, 56% were attributable to gastric, hepatic, and colonic disease or surgery. Posttraumatic abscesses in younger patients became more frequent. Synchronous suprahepatic and subhepatic abscesses or bilateral abscesses accounted for 19%. Streptococci, Escherichia coli, Klebsiella, and Bacteroides species were the most frequently isolated organisms. Although the overall mortality rate was 40%, the surgical mortality rate decreased from 33% initially to 17% recently. The mortality rate of transperitoneal drainage decreased from 41% to 16%. From 1980 through early 1983, a success rate of 84%, with no fatalities, was achieved in percutaneous radiologic drainage of 25 unilocular abscesses. At present, radiologically guided drainage should be considered for unilocular abscesses and some bilocular ones. Although extraperitoneal, extrapleural surgical drainage remains an expeditious form of treatment, it may give way to radiologic drainage. Transperitoneal drainage is preferable for multifocal abscesses and for many abscesses secondary to complications of intraabdominal surgery.

Adolescent↗
PubMed1984

Arterial injuries during inguinal herniorrhaphy.

In all common forms of inguinal herniorrhaphy, stitches pass either just superficial to the internal iliac artery and vein or through their sheath. Despite the potential for arterial injury, documented cases seem to exist only in the foreign-language literature. We report four cases of arterial injury following inguinal herniorrhaphy in adults. The artery is placed in jeopardy when the transversalis fascia is incorporated in the stitches used to close the medial aspect of the internal inguinal ring. The depth of penetration of the needle and the proximity of the external iliac artery must be accurately judged. Injury can result from direct puncture of the artery or avulsion of one of its branches. Immediate repair of any arterial injury is paramount, and newly subnormal pulses below the inguinal injury are unacceptable. Exposure must be adequate, and division of the floor of the inguinal canal may be necessary for this purpose. Repair may require a simple hemostatic suture, a patch graft, or an interposition graft.

Adolescent↗
PubMed1984

Appendicitis near its centenary.

In an analysis of the first 72 cases treated after the formulation of the appendicitis syndrome in 1886 compared with the experience from 1929-1959 and with 307 randomly selected recent cases, the major therapeutic trend has been an emphasis on appendectomy before perforation and abscess formation occur. The rate of infection nonetheless remains approximately 17%. Although the overall mortality rate has declined from 26% overall (40% for surgery) to 0.8%, the current rate of perforation is 28%, with a diagnostic accuracy of 82%. Among 13,848 patients from several reports the perforation rate increases linearly with diagnostic accuracy; therefore, a balance must be sought. Delay awaiting a diagnosis is a major determinant of perforation, but diagnostic aids are of limited help. Clinical acuity and prudent decisiveness are the keys to proper action.

Anti-Bacterial Agents↗
PubMed1984

Total parenteral nutrition inhibits intestinal adaptive hyperplasia in young rats: reversal by feeding.

To determine whether the inhibition of intestinal adaptation by total parenteral nutrition (TPN) in young growing animals is reversible, 130 7-week-old rats with 70% resection of the midportion of the small bowel were given an amino acid and glucose TPN solution parenterally or orally or a chow diet for 10 days. After TPN administration, villous height, crypt depth, DNA and RNA content, RNA:DNA ratio, and sucrase activity were decreased. After returning to 4 weeks of chow feeding, rats given TPN achieved similar body weight and 15% greater intestinal length as compared with rats fed chow from the start, although their jejunal villous height, ileal crypt depth, and RNA:DNA were decreased. Therefore, the inhibition by TPN of intestinal adaptation after intestinal resection in young growing rats is largely reversible. Furthermore, oral feeding of a high-calorie, high-protein liquid diet before feeding of a normal diet appears to promote adaptation after intestinal resection in immature, growing rats.

Adaptation, Physiological↗
PubMed1984

Host-artery weakness in the etiology of femoral anastomotic false aneurysms.

From 1970 through 1980, 47 patients developed a total of 69 false femoral artery aneurysms. Of these aneurysms, 58 occurred an average of 6.2 +/- 3.1 (SD) years after the original revascularization procedure. Ten of these aneurysms occurred once after initial repair and one occurred a second time. Endarterectomy was performed in almost one third of the arteries that later developed false aneurysms. Aneurysms developed in 18 endarterectomized arteries after performance of an anastomosis with a vein patch or Dacron graft. Infection was present in only one case. The suture material in the primary anastomosis was predominantly braided Dacron. Hypertension and bleeding were not commonly associated. Endarterectomy weakens anastomoses and is a factor in false aneurysm formation.

Aged↗