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Biomedical subjects

M B Adams

Publications and source records attributed to M B Adams.

At least 109 records · Page 6Linked to original sources
PubMed1985

Transport of glycyl-L-proline by human intestinal brush border membrane vesicles.

This study characterizes the transport of [1-14C]glycyl-L-proline into purified brush border membrane vesicles prepared from human small intestine. Time-course uptake curves of glycyl-L-proline were similar under sodium thiocyanate or potassium thiocyanate gradient conditions (extravesicular greater than intravesicular) and did not show any overshoot phenomena. The transport of glycine and proline, however, was stimulated by the presence of sodium gradient. Measurement of peptide uptake with increasing medium osmolarity showed that glycyl-L-proline was transported into an osmotically reactive intravesicular space with insignificant binding to the surface of the vesicles. Only 2% of the glycyl-L-proline in the incubation media was hydrolyzed after 10 min of incubation. Also, there was no hydrolysis of peptide transported into the intravesicular space. The effects of increasing concentrations of glycyl-L-proline on uptake showed that uptake of the peptide was saturable and conformed to Michaelis-Menten kinetics with a Km of 4.1 +/- 0.5 mM and a Vmax of 1.53 +/- 0.07 nmol/mg protein X 0.5 min. Free amino acids did not inhibit the transport of glycyl-L-proline while dipeptides and tripeptides exerted appreciable inhibition (up to 60%). Our results show that human small intestinal brush border membrane vesicles transport glycyl-L-proline as an intact peptide by a carrier-mediated, Na+-independent process.

Amino Acids↗
PubMed1985

Evaluation of canine renal transplants with pulsed Doppler duplex sonography.

Preliminary studies of human renal transplants suggested that pulsed Doppler sonography may complement other studies of renal transplant dysfunction. To further evaluate the Doppler technique, 11 dogs who received renal transplants were examined a total of 50 times. No antirejection chemotherapy was used, and following rejection the kidneys were removed and examined histologically. The canine transplants underwent accelerated acute or hyperacute rejection. A pulsed Doppler index (PDI) was derived to quantitate patterns of renal blood flow and peripheral vascular resistance. Arterial Doppler signals were obtained from renal transplant branch vessels in vivo and the PDI consistently fell as rejection occurred. No arterial signals were obtained from one kidney which was subsequently proven to have arterial thrombosis. Pulsed Doppler analysis provides new information about renal transplant blood flow patterns and may demonstrate evidence of rejection and renal arterial occlusion.

Animals↗
PubMed1985

Bacteriophage L: chromosome physical map and structural proteins.

Restriction endonuclease cleavage site mapping was used to locate the regions of highest sequence homology in the chromosomes of Salmonella typhimurium bacteriophages L and P22. These lie in the DNA packaging, tail, early transcription antitermination, and perhaps integration "gene modules." Other regions of the two genomes are substantially less closely related. Phage L, which has no functional immunity I region, lacks approximately 1300 bp of DNA when compared to P22 in this section of the chromosome. At least some of the virion structural proteins are interchangeable between the two phages, which suggests that the two phage structural protein genes are very closely related. In addition, the apparent molecular weights of most P22 and L phage structural proteins are very similar. However, the phage L virion contains about 140 molecules of a 15K capsid protein which apparently has no P22 analog.

Chromosome Mapping↗
PubMed1985

Severe bleeding diathesis associated with invasive aspergillosis in transplant patients.

A severe bleeding disorder developed in eight renal transplant patients with invasive aspergillosis. The hemorrhagic diathesis was characterized by wound oozing, severe upper and lower gastrointestinal tract hemorrhage, and mucosal bleeding at other sites. This unusual coagulopathy was characterized by a prolonged thrombin time, which was corrected with protamine sulfate, and an abnormal Reptilase time. The bleeding disorder antedated the diagnosis of invasive aspergillosis in all cases. The probability that the coagulopathy was due to proteolytic enzymes elaborated by Aspergillus sp. is discussed.

Adult↗
PubMed1985

Assembly-controlled autogenous modulation of bacteriophage P22 scaffolding protein gene expression.

In the assembly of bacteriophage P22, precursor particles containing two major proteins, the gene 5 coat protein and the gene 8 scaffolding protein, package the DNA molecule. During the encapsidation reaction all of the scaffolding protein molecules are released intact and subsequently participate in further rounds of DNA encapsidation. We have previously shown that even though it lies in the center of the late region of the genetic map, the scaffolding protein gene is not always expressed coordinately with the remainder of the late proteins and that some feature of the phage assembly process affects its expression. We present here in vivo experiments which show that there is an inverse correlation between the amount of unassembled scaffolding protein and the rate of scaffolding protein synthesis and that long amber fragments of the scaffolding protein can turn down the synthesis of intact scaffolding protein in trans. These results support a model for scaffolding protein regulation in which the feature of the assembly process which modulates the rate of scaffolding protein synthesis is the amount of unassembled scaffolding protein itself.

Capsid↗
PubMed1985

Bacteriophage P22 tail protein gene expression.

We have found that mutations which block bacteriophage P22 head assembly at or before the DNA packaging stage (1-, 2-, 3-, 5-, and 8-) cause up to a 20-fold increase in the amount of tail (gene 9) protein made during infection. This correlation seems strong enough to warrant consideration of a control mechanism in which the failure to package DNA per se causes a large increase in the synthesis of tail protein. Our results indicate that one of the repressors required for maintenance of lysogeny, the mnt gene product, may be partially responsible for this phenomenon.

Electrophoresis, Polyacrylamide Gel↗
PubMed1985

Posttranscriptional modulation of bacteriophage P22 scaffolding protein gene expression.

The bacteriophage P22 late operon contains 2 genes whose products are required for cell lysis and 13 genes whose products are involved in the morphogenesis of the phage particle. This operon is under the positive control of the phage gene 23 product and is thought to have a single promoter. The expression of one of these late genes, the scaffolding protein gene, is autogenously modulated independently from the remainder of the late genes. When unassembled, scaffolding protein turns down the rate of synthesis of additional scaffolding protein, and when it is assembled into phage precursor structures, it does not. Experiments presented here show (i) that the mRNA from the scaffolding protein gene is functionally threefold more stable when most of the scaffolding protein is assembled than when it is unassembled and (ii) that no new promoter near the scaffolding protein gene is activated at the high level of synthesis. These data support the model that this autogenous modulation occurs at a posttranscriptional level. We also observed that another message, that of coat protein, appears to become increasingly stable with time after phage infection.

Base Composition↗
PubMed1985

Colonic perforation in renal transplant patients.

Review of 713 renal transplant patients at the Medical College of Wisconsin yielded 17 (2.3%) with spontaneous colon perforation. The cause seemed to be related to nonocclusive ischemia in the majority of cases (nine). The sigmoid colon was the most common site of perforation (nine cases). The early detection of colon perforation suspected on radiographic examination was associated with improved survival statistics.

Adolescent↗
PubMed1984

Effect of primary renal disease in patients with renovascular insufficiency.

The effect of laboratory evidence of renal parenchymal abnormality on the results of renal revascularization in 83 patients with renovascular hypertension was determined. Primary renal disease (PRD) was defined as an abnormal urinalysis (proteinuria, hematuria, or casts) in the absence of urinary infection, or decreased renal function (elevated serum creatinine level greater than 1.5 mg/dl and/or decreased creatinine clearance). All patients were hypertensive on medical therapy preoperatively. Patients were defined as cured if postoperative diastolic blood pressure (BP) was less than 90 mm Hg on no medication and improved if BP less than 90 mm Hg on medication. Sixty-six patients (80%) were cured or improved following revascularization. Of 45 patients (63%) with evidence of PRD preoperatively, 28 (62%) were cured or improved compared with 33 patients without PRD, of whom all (100%) were cured or improved (p less than 0.001). Each of five patients with transplant renal artery stenosis had two operations; four were cured or improved. The serum creatinine level was elevated preoperatively in 37 cases. Eighteen of the 37 (49%) improved to within normal limits following operation. Fifteen patients had simultaneous bilateral renal artery revascularization, and 12 (80%) were cured or improved. Fourteen patients (17%) had concomitant vascular procedures: aortobifemoral bypass (seven), abdominal aneurysm resection (five), femoral endarterectomy (one), and aortoiliac bypass (one). Twelve of these 15 patients had PRD, and 8 of the 12 (67%) were cured or improved. Only one death occurred in the perioperative period. Thirty-eight patients (46%) had been treated for hypertension for more than 12 months before referral.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1983

Early renal failure in Fabry's disease.

Two young males were observed with renal failure from Fabry's disease. These two patients had progressive decrease of renal function and required hemodialysis at ages 16 and 24. Diagnosis was confirmed by low plasma galactosidase levels and by skin and kidney biopsy. Each has had a successful kidney transplant with good graft function, the 16-year-old patient for five years and the 24-year-old for two years. Although the renal impairment usually does not appear until the fourth or fifth decade of life. Fabry's disease should be considered in the differential diagnosis of renal failure in young males.

Adolescent↗
PubMed1983

On the sequential packaging of bacteriophage P22 DNA.

Bacteriophage P22 is thought to package daughter chromosomes serially along concatemeric DNA. We present experiments which show that the average DNA packaging series length increases with time after infection, which supports this model. In addition, we have analyzed the effect on average series length of lowering the amount of the various individual proteins involved in DNA packaging. These results support the notion that the protein products of gene 2 and gene 3 are both more stringently required for initiation of sequential DNA packaging series than for their extension, and they are compatible with a model for the control of series length in which that length is determined, at least in part, by a competition between series initiation events and extension events.

Coliphages↗
PubMed1982

Intraoperative biliary endoscopy.

We examined the incidence of "missed" biliary calculi in a teaching center where intraoperative biliary endoscopy is performed routinely. During a six-year period, 1,280 procedures were performed for benign biliary disease. Two hundred eight patients (16%) underwent common duct explorations with choledocholithiasis discovered in 152 patients (73%). Choledochoscopy, using a rigid endoscope equipped with the Hopkins rod-lens system, was performed in 148 patients. When the scope was used, missed stones were seen on a follow-up T-tube cholangiogram in only 2.3% of the patients undergoing choledocholithotomy. More than 90% of the procedures were performed by supervised resident surgeons who had had no specialized training in biliary endoscopy. The incidence of retained stones after choledocholithotomy and choledochoscopy was lower than those of other reported series in which the choledochoscope was not used. We recommend routine use of intraoperative biliary endoscopy in all patients who undergo common duct exploration.

Common Bile Duct↗
PubMed1982

Evaluation of renal transplants with pulsed Doppler duplex sonography.

Sixty-seven patients who had had renal transplants were examined 184 times by pulsed Doppler duplex sonography, and a pulsed Doppler index (PDI) was developed to provide an indicator of renal blood-flow patterns. Arterial Doppler signals were obtained from transplant vessels during all technically satisfactory examinations of viable allografts; interpretations of transplant status based on the PDI and clinical function studies agreed with radionuclide renogram diagnoses in more than 90 per cent of cases when both sonograms and renograms were available. Pulsed Doppler analysis may differentiate between arterial occlusion and severe rejection and may decrease the need for radionuclide studies in some patients.

Graft Rejection↗