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Biomedical subjects

R Meyer

Publications and source records attributed to R Meyer.

At least 343 records · Page 19Linked to original sources
PubMed1982

Metabolism of immunoglobulin A in lactating mice: origins of immunoglobulin A in milk.

The metabolism of albumin and IgA was studied in normal and lactationg mice. Lactation resulted in significant changes in the metabolism of these proteins. The serum albumin concentration was lowered from 47 mg/ml in normals to 24 mg/ml in lactating mice. However, only a slight decrease in the serum concentration of IgA was observed during lactation. The proportion of polymeric and monomeric IgA in serum and milk was evaluated by gel exclusion chromatography. The onset of lactatin led to a rise in the proportion of polymeric IgA (P-IgA) in serum from 37% to 51%. The proportion of P-IgA in milk was 65% and remained constant throughout lactation. P-IgA and albumin were shown to be efficiently transferred from the serum of lactating mice into their milk. Serum decay studies were performed to evaluate the turnover of the serum pools during lactation. The rates of disappearance from the serum of isotopically labeled albumin and P-IgA were observed to increase dramatically during lactation, suggesting that both of these two mild proteins might be derived at least in part from the serum. The sites of synthesis of mild IgA (local vs. extra-mammary gland) were evaluated by determining the extent of dilution of isotopically labeled serum IgA during transport through the mammary gland into the milk. Early in lactation, the majority of the IgA in mouse milk appeared to be derived from distant sites and transferred via the blood to the mammary gland. However, by day 8 of lactation, the isotopically labeled P-IgA in milk was significantly diluted by the IgA synthesized in the mammary gland. Albumin and IgG were not diluted by local synthesis indicating that these proteins were exclusively serum-derived.

Animals↗
PubMed1982

Multiclinic controlled trial of diltiazem for Prinzmetal's angina.

To assess the efficacy of a new calcium entry blocker, diltiazem (Cardizem), for prophylaxis of Prinzmetal's angina, 48 patients were studied in randomized, multiple crossover multiclinic study (2 weeks single-blind, 8 weeks double-blind). Diltiazem dosage in one crossover phase was 120 mg per day; in the other, 240 mg per day. Therapeutic response was measured by patients' diary records of angina frequency and nitroglycerin tablet consumption. Treatment with 120 mg of diltiazem per day reduced angina by 41 percent from the entry placebo period and 20 percent from the paired placebo period (p less than 0.005). Treatment with 240 mg of diltiazem per day reduced angina frequency by 68 percent from the entry placebo period and 43 percent from the paired placebo period (p less than 0.01). There were similar reductions in nitroglycerin consumption. Adverse experiences that may have been related to the medication were noted in only 5 percent of patients. There were no alterations in blood pressure or heart rate. The PR interval increased 3 percent at the 240 mg dosage level. We conclude that diltiazem is an effective and safe agent for control of symptoms of Prinzmetal's angina.

Adult↗
PubMed1982

Long-term vasotonus behavior of the microvasculatory system of heart and skeletal muscle in rats exercised by swimming.

A new histomorphometric method was used to study the hitherto unknown long-term vasotonus behavior of the arterial microvasculatory system. The right and the left ventricular walls of 29 rats exercised by swimming (48 hours in 4 weeks), and 30 control animals, as well as the musculus rectus femoris of 5 experimental and 5 control animals were investigated. The walls of arterial microvessels of the right ventricular wall and of the skeletal muscle of trained rats were significantly thicker indicating a long-term vasotonus increase. In the microvasculature of the lift ventricular wall no differences were found in comparison to control animals. In view of the vasotonus increase in the right ventricular wall and skeletal muscle, one can assume that tonus-decreasing factors of nearly the same intensity and/or duration of efficiency have opposed the tonic influences in the left-ventricular microvessels, thus preventing a thickening of vessel walls.

Adenosine Triphosphatases↗
PubMed1982

Genitourinary tract injuries due to fracture of the pelvis in females: sequelae and their management.

The pathophysiology of injury to the female genitourinary tract secondary to a fractured pelvis has been studied in 5 patients. Delayed complications were frequent and their management is described. It is concluded that a transpubic approach to the lower urinary tract facilitates the satisfactory reconstruction of the urinary tract. Long-term follow-up of 4 to 5 years is necessary for the satisfactory management of these patients following their initial injury.

Adolescent↗
PubMed1982

Properties of R1162, a broad-host-range, high-copy-number plasmid.

Regions of plasmid DNA encoding characteristic properties of the IncQ (P-4) group plasmid R1162 were identified by mutagenesis and in vitro cloning. Coding sequences sufficient for expression of incompatibility and efficient conjugal mobilization by plasmid R751 were found to be linked to the origin of DNA replication. In contrast, there was a region remote from the origin, and active in trans, that was required for plasmid maintenance. A derivative that was temperature sensitive for stability was isolated. The defect mapped at or near the region required for plasmid maintenance and resulted in far fewer copies of supercoiled plasmid DNA per cell under permissive conditions. A second region required for stability was also identified from the behavior of a deletion derivative of R1162, which did not, however, show an altered number of supercoiled plasmid DNA copies. Finally, a plasmid DNA mutation resulting in a substantially higher copy number was isolated. Plasmid reconstruction experiments suggested that the mutation was linked to the replicative origin.

Base Sequence↗
PubMed1982

Broad-host-range IncP-4 plasmid R1162: effects of deletions and insertions on plasmid maintenance and host range.

R1162 is an 8.7-kilobase (kb) broad-host-range replicon encoding resistance to streptomycin and sulfa drugs. In vitro deletion of 1.8-kb DNA between coordinates 3.0 and 5.3 kb did not affect plasmid maintenance, but a Tn1 insertion at coordinate 6.3 kb led to a recessive defect in plasmid maintenance. The only cis-acting region necessary for plasmid replication appears to lie between the Tn1 insertion at coordinate 6.3 kb and a second Tn1 insertion at coordinate 6.5 kb. All R1162 sequences between position 6.5 kb and the EcoRI site at coordinate 8.7/0 kb were dispensible for replication in Escherichia coli and Pseudomonas putida. Plasmids carrying insertions in a variety of restriction sites in an R1162::Tn1 derivative were unstable in P. putida but stable in E. coli. Tn5 insertions in R1162 showed a hot spot at coordinate 7.5 kb. A Tn5 insertion at coordinate 8.2 kb appeared to mark the 3' end of the streptomycin phosphotransferase coding sequence. All R1162::Tn5 derivatives showed specific instability in Pseudomonas strains but not in E. coli. The instability could be relieved by internal deletions of Tn5 sequences. In the haloaromatic-degrading Pseudomonas sp. strain B13, introduction of an unstable R1162::Tn5 plasmid led to loss of ability to utilize m-chlorobenzoate as a growth substrate. Our results showed that alteration of plasmid sequence organization in nonessential regions can result in restriction of plasmid host range.

Base Sequence↗
PubMed1982

Multiple mechanisms for expression of incompatibility by broad-host-range plasmid RK2.

By cloning fragments of plasmid DNA, we have shown that RK2 expresses incompatibility by more than one mechanism. One previously identified (R. J. Meyer, Mol. Gen, Genet. 177:155--161, 1979; Thomas et al., Mol. Gen. Genet. 181:1--7, 1981) determinant for incompatibility is linked to the origin of plasmid DNA replication. When cloned into a plasmid vector, this determinant prevents the stable inheritance of a coresident RK2. However, susceptibility to this mechanism of incompatibility requires an active RK2 replicon and is abolished if another replicator is provided. We have also cloned a second incompatibility determinant, encoded within the 54.1- to 56.4-kilobase region of RK2 DNA, which we call IncP-1(II). An RK2 derivative remains sensitive to IncP-1(II), even when it is not replicating by means of the RK2 replicon. The 54.1- to 56.4-kilobase DNA does not confer susceptibility to the IncP-1(II) mechanism, nor does it encode a detectable system for efficient plasmid partitioning. The incompatibility may be related to the expression of genes mapping in the 54.1- to 56.4-kilobase region, which are required for plasmid maintenance and suppression of plasmid-encoded killing functions.

Cloning, Molecular↗
PubMed1981

Single bilobed flap for use in head and neck reconstruction.

A new bilobed cutaneous and myocutaneous flap providing ipsilateral reconstruction possibilities in the head and neck is described. The flap incorporates the pectoralis major myocutaneous flap and the medially based deltopectoral flap in a single bilobed flap. Both flaps come from the same side to provide bulk and cutaneous coverage in a single flap.

Adenocarcinoma↗