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Biomedical subjects

R A Malt

Publications and source records attributed to R A Malt.

At least 127 records · Page 7Linked to original sources
PubMed1979

Tests and management affecting survival after portacaval and spenorenal shunts.

New data were derived from records of 115 patients undergoing portacaval or spenorenal shunts from 1966 to 1973. The last serum bilirubin level determined before a shunt was the best predictor of operative mortality. The strongest predictor of long term survival was the first serum albumin level measured after admission. Operative mortality was strongly correlated with intraoperative clotting disorders; however, the prothrombin time and the partial thromboplastin time predicated long term survival. Clinical assessment added unique information to conclusion derived from laboratory tests. Results of operation were independent of the skill and experience of the surgeon, except that the best risk patients perhaps may have done better when operated upon by the most experienced surgeons. Once a patient has stabilized after a bleeding episode, he might as well be operated upon at the same admission rather than be discharged to be operated upon at a later arbitrary time.

Ascites↗
PubMed1979

Enhanced colonic carcinogenesis with azoxymethane in rats after pancreaticobiliary diversion to mid small bowel.

Since biliary excretion of metabolites might determine the pattern of intestinal neoplasms induced by azoxymethane, the number and distribution of tumors were studied in rats after pancreaticobiliary diversion to the mid small bowel. Pancreaticobiliary diversion was performed either immediately before the first of 16 weekly injections of azoxymethane or 10 days after the last. Seven months after pancreaticobiliary diversion, persistent ileal hyperplasia was manifested by higher levels of mucosal RNA and DNA compared with controls (34--102%: P less than 0.001), while there was little residual adaptation in the colon. Qualitative and quantitative analysis of fecal bile acids 6--26 wk after pancreaticobiliary diversion showed few differences. Pancreaticobiliary diversion doubled the incidence of colonic tumors, whether operation preceded (P less than 0.005) or followed (P less than 0.02) the course of azoxymethane. Suture-line tumors were common in the small bowel, particularly in the transposed duodenal stump. Despite intense ileal hyperplasia as a consequence of pancreaticobiliary diversion, the ileum remained resistant to chemical carcinogenesis. The potentiation of colonic neoplasms by pancreaticobiliary diversion probably depends on the stimulation of colonic mucosal proliferation.

Adenocarcinoma↗
PubMed1979

Ileal resection potentiates 1,2-dimethylhydrazine-induced colonic carcinogenesis.

The effect of colonic hyperplasia produced by resection of the distal third of the small bowel (DSBR) on the development of chemical carcinogenesis of the colon by dimethylhydrazine (DMH) was tested in rats. For the most part the amounts of RNA and DNA in the small bowel were the same with the combined treatments as with either one alone; quantities of nucleic acids tended to increase only in transverse and distal colon. After 37 weeks the number of neoplasms per rat was increased six-fold by combining DSBR with DMH. Neoplasms were spread throughout the colon after combined treatment as opposed to the ascending colong after DMH alone. Postresectional hyperplasia appears to increase the incidence and distribution of colon tumors.

Animals↗
PubMed1979

Alterations in the relative abundance of specific messenger ribonucleoproteins associated with compensatory renal hypertrophy.

A possible role of messenger RNA (mRNA)-associated proteins during compensatory renal hypertrophy in modulation of mRNA biogenesis has been examined in this investigation. Renal cytoplasmic free messenger ribonucleoprotein (CF mRNP) and polysomal mRNP (PA mRNP) have been isolated from kidney following 48 hours of compensatory renal hypertrophy, and the relative amounts of proteins associated with CF mRNP and PA mRNP in control and hypertrophying mouse kidney are compared. (CF mRNP refers to nonpolysomal messenger ribonucleoprotein found in the subribosomal region of sucrose gradients. PA mRNP or polysome-associated mRNP refers to mRNP released from polysomes.) CF mRNP has a buoyant density of 1.3 to 1.44 gm. per ml., contains RNA that sediments at 5 to 22 Svedberg units, and has a protein moiety comprising at least 15 polypeptides as revealed by sodium dodecyl sulfate polyacrylamide gels. PA mRNP contains three major polypeptides (molecular weights, 77,000, 52,000 and 17,000). Following 48 hours of compensatory renal hypertrophy, the relative amounts of proteins are changed: a 44,000- and 52,000- molecular weight polypeptide in CF mRNP is increased, a 52,000-molecular weight polypeptide in PA mRNP is reduced, and a 17,000-molecular weight polypeptide in PA mRNP is increased.

Animals↗
PubMed1978

Randomized trial of emergency mesocaval and portacaval shunts for bleeding esophageal varices.

A randomized trial of emergency portacaval or mesocaval shunting was conducted in twenty-four cirrhotic patients bleeding from esophageal varices. The group of eleven patients having mesocaval shunts was comparable to the group having portacaval shunts in age distribution, sex, and preoperative physical condition. Postoperative fatality rates were 46% after portacaval shunting and 73% after mesocaval shunting. Results favor portacaval shunts for the emergency control of bleeding varices in the spectrum of patients seen in an urban hospital.

Adult↗
PubMed1978

Side-to-side portacaval shunt versus nonsurgical treatment of Budd-Chiari syndrome.

Although a side-to-side portacaval shunt will relieve some patients with Budd-Chiari syndrome, distinction between relief as a result of operation and spontaneous recovery may be inexact. A nonshunting operation relieved one of two patients as much as a side-to-side portacaval shunt did. In these two patients and one additional patient, streptokinase therapy may have been beneficial.

Adult↗
PubMed1978

Clinical correlates of resectability and survival in gastric carcinoma.

The course of 201 patients with carcinoma of the stomach treated from 1962 through 1966 was followed with 97% determinacy for 10 years. The actual five year survival rate was 11%; the ten year rate was 7%. The mean duration of survival was 5.8 +/- 2.7 (S.D.) months. These results were similar to those reported for the period 1922-1926. Survival was strongly correlated with the surgeon's assessment after exploration. All patients alive after five years had operations thought to be curative, usually partial gastrectomies; the survival rate of this group was 24%. Gastroenterostomy was ineffectual palliation. Better results will require nonsurgical adjuncts, since the correlates of survival are those of minimally invasive cancer.

Aged↗
PubMed1978

Proximal enterectomy stimulates distal hyperplasia more than bypass or pancreaticobiliary diversion.

To determine the contribution of intraluminal factors to postresectional intestinal hyperplasia, cell proliferation in the distal intestine of male rats was studied after 50% proximal enterectomy or 50% proximal bypass and also after transposition of the duodenal papilla to the mid small bowel. Within 48 hr all three operations increased RNA and DNA content s in the ileal mucosa 16 to 50% over control values. At 48 hr and 1 week the response distal to resection exceeded that of bypass or pancreaticobiliary diversion; nucleic acid contents, DNA specific activity, villous height, crypt depth, and luminal circumference were greatest 1 week after resection. By 1 month, however, chemical and histological values after resection were equalled or surpassed by those in the other two groups. In excluded jejunum itself, mucosal atrophy lowered RNA and DNA contents to 60% of control levels 1 month postoperatively. Neither pancreaticobiliary diversion nor proximal enteric bypass produces the same rate of distal hyperplasia as proximal resection. Modest colonic hyperplasia may contribute to intestinal adaptation after proximal enterectomy. Adaptive postrescetional cell proliferation appears not to be mediated simply by intraluminal nutrition or enteric secretions; hormonal factors may also be important.

Animals↗
PubMed1978

Contributions of bile and pancreatic juice to cell proliferation in ileal mucosa.

To determine the relative contributions of bile and pancreatic juice to adaptive intestinal hyperplasia, cell proliferation in rat ileal mucosa was studied after supplying bile alone or the combined pancreaticobiliary effluent direct to mid-small bowel. Bile was routed through the choledochus cannulated above the pancreas. Pancreaticobiliary secretions were diverted through a transposed duodenal segment containing the papilla. Diversion of bile into the mid-bowel with and without pancreatic juice caused similar increases in ileal ribonucleic acid (RNA) (16% to 50%) and deoxyribonucleic acid (DNA) (22% to 41%) contents at both 48 hours and 1 week after operation. Specific activity of DNA after injection of tritiated thymidine was greatest after diversion of the combined effluent. After 1 month nucleic acid contents in the upper ileum after pancreaticobiliary diversion were 37% to 59% higher than after transection or biliary diversion (P less than 0.005). Likewise, after biliary diversion villous height and crypt depth were increased only at 1 week, but after diversion of both secretions increases were found at 1 week and 1 month. High luminal concentrations of bile cause transient cell proliferation in ileal mucosa, but the additional presence of pancreatic juice prolongs this adaptive response.

Adaptation, Physiological↗
PubMed1978

Compensatory hyperplasia with increasing loss of renal mass.

When a rat with two kidneys is cross-circulated with an anephric rat, compensatory renal hypertrophy occurs as indicated by an increased ratio of RNA to DNA within 6 hours and an increased ratio of kidney weight to body weight within 12 hours. Removal of three kidneys between the rats further increases residual renal mass and RNA/DNA after 24 and 48 hours of cross-circulation as compared with results of removing two kidneys. Trinephrectomy triples the mitotic index and doubles the proliferative index. Increasing the magnitude of renal loss causes appreciable hyperplasia as well as increasing the magnitude of compensatory renal hypertrophy.

Animals↗
PubMed1978

Humoral stimulation of cell proliferation in small bowel after transection and resection in rats.

Possible humoral involvement in the control of postresectional intestinal adaptation was tested in individual rats and in pairs of rats connected in vascular parabiosis for 48 hr. In individual rats, transection of the jejunum produced transient mucosal hyperplasia in the mid and distal small intestine, independent of the effect of laparotomy and of handling the bowel. Jejunal resection caused more intense and sustained distal hyperplasia, with increases in midbowel RNA content (38%), DNA content (16%), and DNA specific activity (68%) over values 48 hr after transection. In parabiotic rats, both transection and resection of the jejunum in one partner stimulated mucosal uptake of [H]TdR in the intact parabiont; increments of 59 to 128% in total radioactivity and in specific activity of DNA were found in the mid and distal small intestine of the intact parabiont. Because only rats actually undergoing abdominal operations had higher mucosal nucleic acid contents than their parabiotic partners, the transmitted response was weaker than the direct response. Systemic factors as well as local (topical) stimulators appear to be involved in adaptation of the shortened gut.

Animals↗
PubMed1978

Promotion of azoxymethane-induced colonic neoplasia by resection of the proximal small bowel.

Potential enhancement of intestinal neoplasia by compensatory mucosal hyperplasia was tested in rats subjected to 50% proximal small bowel resection (PSBR) 10 days after the last of 16 weekly injections of azoxymethane. Azoxymethane alone increased jejunal contents of RNA and DNA each by 26% at 17 to 18 weeks (p less than 0.01) before there was macroscopic evidence of neoplasia. Three months after PSBR alone, ileal hyperplasia was characterized by increased amounts of RNA (42 to 76%) and DNA (68 to 95%), taller villi, deeper crypts, and luminal dilation (p less than 0.05 to 0.001); however, the colon showed only patchy hyperplasia. When the combined effects of azoxymethane and PSBR were observed 26 to 30 weeks after the first injection, rats with PSBR had an increased number of colonic tumors per animal (2.9 versus 1.6 for controls; p less than 0.02). Despite the intense ileal hyperplasia produced by PSBR, ileal neoplasia did not occur. Enhanced colonic carcinogenesis followed sequential exposure of the mucosa to the carcinogen (azoxymethane) and to the promoting factor (PSBR).

Adaptation, Physiological↗
PubMed1977

Ribosomal proteins of mouse kidney: normal status and during compensatory renal hypertrophy.

Ribosomes were isolated from normal and growing kidney and the protein complement was examined by a two-dimensional gel electrophoretic procedure. Proteins were resolved in the first dimension on the basis of charge and, in the second dimension, on the basis of molecular weight. 60S and 40S ribosomal subunits from normal kidney contained respectively 42 and 31 proteins. 80S ribosomes contained 23 proteins not found with either sub-unit. Nineteen of these proteins were removed from the ribosomes when isolated ribosomes were washed in a high salt buffer. Six proteins of the 80S ribosome corresponded to proteins associated with both sub-units. 80S ribosomal proteins were also studied during compensatory renal hypertrophy after 4-96 h of induced growth. The protein complement displayed by electrophoresis was identical to the pattern seen from normal renal cells.

Animals↗