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Biomedical subjects

R M Davis

Publications and source records attributed to R M Davis.

At least 127 records · Page 7Linked to original sources
PubMed1986

Transmission of measles in medical settings. 1980 through 1984.

For the five-year period 1980 through 1984, a total of 241 persons with measles in 30 states were identified as probably having acquired their infection in a medical facility. The proportion of all measles cases acquired in medical settings increased from 0.7% for 1980 through 1982 to 2.9% for 1983 and 1984. Seventy-six percent of cases were found in patients or visitors, and 24% in personnel at the medical facility where transmission occurred. The highest proportion of cases occurred in children less than 5 years of age (54.3%), followed by persons 25 to 29 years of age (14.7%). Of spread (50.0%) and patient-to-staff spread (36.7%) were most common. Medical personnel rarely transmitted disease to others. More attention needs to be given to methods of preventing spread of measles in medical facilities, such as isolation precautions, postexposure prohylaxis of potential contacts (vaccination or immune globulin), and ensuring that medical personnel are immune to measles.

Adult↗
PubMed1986

Late orbital implant migration.

A 29-year-old woman underwent two orbital explorations in 12 years after orbital floor fracture repair with placement of a silicone implant. Recurrent diplopia, proptosis, and pain developed, suggesting an insidious orbital process. Computed tomography findings were instrumental in the patient's diagnostic evaluation.

Adult↗
PubMed1985

Major impediments to measles elimination. The modern epidemiology of an ancient disease.

Great success has been achieved in controlling measles in the United States with a greater than 99% reduction in incidence rate from the prevaccine era. However, since 1981, the incidence rate of measles in the United States has been relatively stable at approximately 1,500 to 3,000 reported cases annually. We reviewed available information to determine the remaining impediments to elimination of measles. The potential impediments can be divided into two categories: (1) implementation of the current strategy and (2) whether the current strategy needs modification. The major reason for the failure to achieve elimination appears to be the fact that some persons for whom vaccine is indicated have not been vaccinated. While vaccine failures and importations play a role in transmission, sustained transmission in a totally vaccinated community has not been demonstrated. All chains of transmission have involved some unvaccinated persons. Measles elimination will require complete implementation of current strategies and careful monitoring of epidemiologic trends to determine whether future modifications in strategy are needed.

Child↗
PubMed1985

Proteases in human lenses and their possible significance.

Proteases identified as exopeptidases including dipeptidyl II and III, phenylalanine, leucine, methionine, lysine and alanine aminopeptidases, and prolyl endopeptidase were found in extracts of human fetal lenses. Previous data from normal adult lenses were included for comparison. Except for prolyl endopeptidase and dipeptidyl peptidase II, all protease activities were lower in fetal lenses.

Aminopeptidases↗
PubMed1985

Proteases in the Emory mouse cataract.

Exopeptidases identified as dipeptidyl peptidase III and leucine aminopeptidase, and an endopeptidase, prolyl endopeptidase, were found in the Emory Mouse cataract and the Cataract Resistant mouse lens extracts. The specific activity measured on Arg-Arg-2-NNap for DPP III and the hydrolysis of Boc-Arg-Pro-2-NNap for prolyl endopeptidase were higher in the Emory Mouse cataractous lens extract. A relatively high rate of hydrolysis of the beta-naphthylamide of leucine aminopeptidase was present in both mouse categories; however, the Cataract Resistant mouse lens had approximately double the protease activity of the Emory Mouse cataract.

Animals↗
PubMed1984

Purification of a human urinary carboxypeptidase (kininase) distinct from carboxypeptidases A, B, or N.

A carboxypeptidase which cleaves basic C-terminal amino acids from peptides was purified from concentrated human urine by a three-step procedure: chromatography on Affi-Gel Blue, arginine-Sepharose affinity chromatography, and gel filtration by HPLC on a TSK-G3000SW column. Urinary carboxypeptidase was purified 406-fold with an 11% yield and a specific activity of 49 mumol/min/mg with benzoylglycylargininic acid as substrate. It migrated as a single band of Mr 75,700 in polyacrylamide gel electrophoresis with sodium dodecyl sulfate. It cleaved benzoylglycylarginine, benzoylglycyllysine, benzoylglycylargininic acid, benzoylalanyllysine, and benzoylphenylalanyllysine at different relative rates than human plasma carboxypeptidase N, the Mr 48,000 active subunit of carboxypeptidase N or human pancreatic carboxypeptidase B. Urinary carboxypeptidase did not hydrolyze benzoylglycylphenylalanine, a substrate of carboxypeptidase A, but readily cleaved bradykinin with a Km of 46 microM and a Kcat of 32 min-1. Its activity was enhanced by CoCl2 and inhibited by cadmium acetate, o-phenanthroline, or DL-2-mercaptomethyl-3-guanidinoethylthiopropanoic acid. The enzyme had a pH optimum of 7.0 and its activity dropped at pH 6.0 by 60%. It was stable for at least 2 h at 37 degrees C (pH 8.0) but was unstable at room temperature below pH 4.5. The molecular weight, electrophoretic mobility, and activity of urinary carboxypeptidase was not affected by trypsin. The effect of pH and stability further distinguished the urinary carboxypeptidase from other human carboxypeptidases. Urinary carboxypeptidase was immunologically distinct from carboxypeptidase N when analyzed by the "Western blot" technique. Thus, human urine contains a basic carboxypeptidase, different from known carboxypeptidases, which may be released into the urine by the kidney. Here it could inactivate kinins and other peptides containing a basic C-terminal amino acid.

Carboxypeptidase B↗
PubMed1984

Latissimus dorsi free flaps in the elderly: an alternative to below-knee amputation.

The purpose of this paper is to document that free-flap surgery may be applied in specific circumstances to elderly patients with extensive vascular insufficiency and wound coverage problems. Below-knee amputation may be a direct but not necessarily desirable answer to the elderly patient with these problems. The problems of increased energy of ambulation, prosthetic fit, and psychological depression are all accentuated in the elderly. Three free-flap patients of an average age of 80 are presented with successful wound coverage, control of ischemic pain, and early return to an independent ambulatory state. The latissimus free flap seems to be an appropriate tool for this purpose. The T-pedicle is especially suited to bridge segmental vascular deficits seen in this population. We conclude that in specific situations, this approach may be an alternative to amputation in the elderly.

Aged↗
PubMed1984

Dipeptidyl peptidase III of human cataractous lenses. Partial purification.

A partial purification of dipeptidyl peptidase III has been achieved from human cataractous lens. The specific activity was increased 45.5-fold over that of the original aqueous extract. The exopeptidase exhibited a marked preference for the release of Arg-Arg from Arg-Arg-2-NNap at the optimum pH 8.8 and 37 degrees. The Km for this substrate was estimated to be 6.061 X 10(-3). Lens DPP III was inhibited by EDTA, p-chloromercuriphenyl sulfonate, puromycin and DFP. The preparation contained leucyl aminopeptidase and a neutral endopeptidase as contaminating proteases.

Cataract↗
PubMed1984

The identification of prolyl endopeptidase in bovine lenses: a preliminary report.

A new neutral endopeptidase having the properties of prolyl endopeptidase was detected in bovine lenses. The enzyme hydrolyzed the prolyl bond in the newly-developed fluorogenic substrate, t-butyloxycarbonyl-Arg-Pro-2-NNap, optimally at pH 8 and 37 degrees. The Km value was estimated to be 0.033 mM. An approximately 4-fold purification was achieved. DFP completely inhibited the hydrolysis of Boc-Arg-Pro-2-NNap by the endopeptidase.

Animals↗
PubMed1981

Cellular DNA damage by nitrosocimetidine: a comparison with N-methyl-N'-nitroso-nitrosoguanidine and x-irradiation.

Permanently proliferating lymphoblastoid cell lines (LCLs) and normal unstimulated peripheral blood leukocytes have been used to study the effects of nitrosocimetidine (NC) on cultured human lymphoid cells. The approaches that were used to assess the cells' ability to cope with NC were: (i) determination of cell survival as measured by colony formation in microtiter plates; (ii) quantitation of DNA synthesis and DNA-repair replication by isopyknic sedimentation of DNA density labeled with 5-bromo-2-deoxyuridine (BrdU); (iii) measurement of the induction of alkali labile lesions and strand breaks by NC in 3H-labeled DNA using velocity sedimentation in alkaline sucrose. In summary, treatment with NC was found to inhibit both replicative DNA synthesis and colony formation in LCLs. At the molecular level, NC treatment induced alkali labile lesions in LCL DNA and elicited DNA-repair replication in proliferating LCLs as well as unstimulated lymphocytes. Considered in total, these data indicate that NC is reactive with human DNA in the cellular environment in a manner similar to methylating nitroso compounds which have been shown to be carcinogenic. The significance of these findings will be discussed.

Ataxia Telangiectasia↗
PubMed1981

Hypothyroidism following removal of a "thyroglossal duct cyst".

This case demonstrates how a midline ectopic thyroid gland can be misdiagnosed as a thyroglossal duct cyst. Awareness of this clinical entity is critical if the diagnosis is to be made preoperatively. Thyroid function tests and a 99mTc or 123I scintiscan of the neck should be performed when evaluating a patient with a midline anterior cervical mass. Although thyroid replacement will often cause regression of the enlarged ectopic thyroid gland, surgical intervention is required if a solid mass persists. When an ectopic thyroid gland has been excised and is subsequently found to be the child's only thyroid tissue, thyroid replacement is necessary. If biopsy of the mass established the diagnosis at the time of surgery, effective treatment consists of longitudinally dividing the tissue and placing each half laterally beneath the strap muscles. When this is done, long-term follow-up and periodic thyroid function tests are advised. If this tissue should become hypoactive, thyroid replacement is then required.

Child↗
PubMed1981

Localisation of male determining factors in man: a thorough review of structural anomalies of the Y chromosome.

It is widely accepted that male determination in man depends on the presence of a factor or factors on the Y chromosome. These factors may be localised within the Y chromosome through the study of structural anomalies of the Y. A thorough review of seven different structural anomalies of the Y is presented: dicentric Y chromosomes, Y isochromosomes, ring Y chromosomes, Y; autosome, Y;X, and Y;Y translocations, and Y deletions. The evidence from these studies indicates that a gene or genes on the short arm or the Y near the centromere play a crucial role in the development of the testes. A few studies indicate that one or more factors on the long arm of the Y may also influence testicular development. If such a factor is present on the long arm, then it too must be very near the centromere. The theory that separate genes independently control the initial development and maturation of the tests (on the long and short arms of the Y, respectively) may be premature. Recently proposed arguments in its favour are examined. Some evidence also indicates the presence of a fertility factor on the non-fluorescent segment of the long arm. Relevant information on the H-Y antigen is discussed.

Adolescent↗