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Biomedical subjects

K H Mayer

Publications and source records attributed to K H Mayer.

At least 145 records · Page 8Linked to original sources
PubMed1986

Genetic and physical characterization of IncM plasmid pBWH1 and its variance among natural isolates.

We present a genetic and physical characterization of the IncM plasmid pBWH1. A physical map was constructed for the enzymes EcoRI, BamHI, SalI, BglII, HindIII, MstII, and XhoI. A series of deletions and a series of subclones of pBWH1 were constructed and used to determine the locations on this map of the transfer region; the replication region; and the genes determining resistance to beta-lactams, chloramphenicol, the sulfonamides, and gentamicin. We compared 51 different isolates, including isolates which had lost individual antibiotic resistances or the transfer phenotype, and showed that variations occurred in all regions of the plasmid genome. Frequently, correlations could be made between phenotypic variation and variation of the EcoRI fragments which contained the gene determining that phenotype.

Chromosome Mapping↗
PubMed1986

Human T-lymphotropic virus type III in high-risk, antibody-negative homosexual men.

A cohort of 215 asymptomatic homosexually active men from a Boston community health center are being prospectively followed to assess the natural history of the human T-lymphotropic virus type III (HTLV-III) infection. To determine if certain asymptomatic persons who are HTLV-III antibody negative may be viremic, an algorithm was developed that defined high-risk characteristics (a sexual partner with the acquired immunodeficiency syndrome [AIDS]; more than 100 homosexual partners; or leukopenia, lymphopenia, neutropenia, or thrombocytopenia). Of 33 asymptomatic homosexual men who did not have antibody to HTLV-III and whose cases have not been previously reported, 2 had HTLV-III recovered from their lymphocytes. Clinical, behavioral, and hematologic data from seronegative persons did not distinguish between those with negative or positive viral cultures. Asymptomatic carriage of HTLV-III in high-risk seronegative persons underscores the need to base preventive educational strategies and behavioral modification on the assessment of risk factors and not solely on the results of HTLV-III antibody screening.

Acquired Immunodeficiency Syndrome↗
PubMed1985

Intercontinental spread of a new antibiotic resistance gene on an epidemic plasmid.

Bacteria of different genera isolated at nine medical centers in different parts of the United States and at one center in Venezuela during the first decade of gentamicin usage carried the gentamicin resistance gene 2"-aminoglycoside nucleotidyltransferase on the same transferable plasmid. Such widespread dissemination of a newly observed resistance gene on one plasmid suggests that a new resistance gene may emerge once on a single plasmid, which then carries it to other centers and other plasmids. The resistance gene might, therefore, be contained if detected early.

Bacteria↗
PubMed1985

[Angiotensin converting enzyme in lung diseases].

The aim of the study was to test the validity of ACE-determination for the differential diagnosis of pulmonary diseases. First details of the method, then the determination of the reference scale are discussed. The ACE-activity in the serum in 60 patients with sarcoidosis and 80 patients with other pulmonary diseases was measured. The sensitivity with which sarcoidosis can be established by means of the ACE-activity is to be examined. No positive correlation between the activity of the enzyme and the x-ray staging could be established, but active diseases requiring treatment could be distinguished from inactive forms to an unexpectedly high degree of reliance in our group of patients. The fact that in some cases of other pulmonary diseases--especially those connected with hepatopathy--higher ACE-activity is found as well, reduces the validity of the method. The determination of ACE comes up to all the criterias of a feasible, clinical-chemical method of analysis: practicability, reliance, high sensitivity and accuracy in a selected group, easy repetition. In some cases a typical x-ray result and corresponding clinical examination may provide the diagnosis of active sarcoidosis without further invasive methods of investigation; observation of the course of disease and adjustment of therapy are possible by means of the control of the ACE.

Alveolitis, Extrinsic Allergic↗
PubMed1985

Resistance to antibiotics in clinical isolates of Klebsiella pneumoniae.

The antibiotic resistance of Klebsiella pneumoniae isolates from 12 medical centers worldwide, over a 1- to 6-year period, were tested. Clinical isolates of K. pneumoniae were resistant to ampicillin and carbenicillin. Resistance to other antibiotics was less frequent with isolates of K. pneumoniae from 5 of 6 US centers than with those from 6 centers outside the US. In nearly all of the centers, resistance to sulfamethoxazole-trimethoprim, gentamicin, tobramycin, or chloramphenicol was more frequent in isolates of K. pneumoniae than in those of Escherichia coli, while the reverse was true for resistance to tetracycline. Resistance to multiple antibiotics declined gradually in isolates of K. pneumoniae at one center, but rose abruptly again with dissemination of a new plasmid.

Ampicillin↗
PubMed1985

Trimethoprim resistance in multiple genera of Enterobacteriaceae at a U.S. hospital: spread of the type II dihydrofolate reductase gene by a single plasmid.

The percentage of clinical isolates of several species of Enterobacteriaceae, particularly Escherichia coli and Klebsiella pneumoniae, resistant to trimethoprim (TMPR) has increased gradually at the Brigham and Women's Hospital (Boston) in recent years. Thirty-seven of 42 TMPR isolates from six species of gram-negative bacilli conjugally transferred TMP resistance to K12 E. coli. beta-Lactam resistance cotransferred from 21 of the 37 donors, and sulfamethoxazole (SMZ) resistance cotransferred from five of the 37 donors. Plasmids that encoded TMP resistance either alone or with SMZ resistance had a molecular size of approximately 52.5 kilobases, with identical restriction endonuclease-generated "fingerprints." Plasmids encoding beta-lactam-mediated resistance (beta R) were approximately four kilobases larger and had fragment patterns that were identical for all of the TMPR/beta R plasmids tested and had many restriction endonuclease-generated bands in common with TMPR plasmids. Radiolabeled dihydrofolate reductase (DHFR) probes identified the type II DHFR as the determinant of TMP resistance. In contrast with reports from Europe, TMP resistance in multiple species of Enterobacteriaceae was found to be spread in one hospital by a single, stable conjugative plasmid that has a wide host range and encodes the type II DHFR gene.

Conjugation, Genetic↗
PubMed1985

Current guidelines on the use of antibacterial drugs in patients with malignancies.

Patients with malignant disease may be predisposed to bacterial infections because of neoplastic disruption of normal tissue barriers, exogenous immunosuppressive therapy (drugs with or without radiation), and intrinsic host immune deficits secondary to these diseases. Diminished polymorphonuclear leucocyte numbers or function and impaired humoral immunity are highly correlated with the development of serious bacterial infections. The usual signs and symptoms of infection may be absent or altered in a compromised host. Therapy must be instituted promptly upon clinical suspicion of bacterial infection, and empirical choices should usually include combinations that are synergistic for likely pathogens based on knowledge of the local predominant flora and susceptibility data. Synergism has most often been demonstrated in combinations that utilise a beta-lactam (semisynthetic penicillin or cephalosporin) and an aminoglycoside. Triple drug therapy has not been shown to be advantageous. Monotherapy with third generation cephalosporins, carbapenems, monobactams, or ureidopenicillins has not been proven to offer advantages over 2-drug regimens for these patients. Granulocytopenic patients who respond to 2-drug therapy but remain neutropenic may need continued treatment until the neutropenia subsides. Those who do not respond and remain febrile with an unclear focus may need to be started on antifungal therapy in addition to the antibacterial agent. The use of oral agents for the prophylaxis of neutropenic patients against bacteraemia remains controversial. If drugs are used, co-trimoxazole and nystatin suspension may be preferable.

Aminoglycosides↗
PubMed1985

Seroepidemiology of human T-lymphotropic virus type III among homosexual men with the acquired immunodeficiency syndrome or generalized lymphadenopathy and among asymptomatic controls in Boston.

We studied a cohort of 45 homosexual men with the acquired immunodeficiency syndrome, 78 with persistent unexplained generalized lymphadenopathy, and 160 asymptomatic homosexual controls for serologic evidence of infection with human T-lymphotropic virus type III (HTLV-III). Study participants were recruited from a community-based health center and a university hospital practice. Ninety-eight percent of men with the syndrome and greater than 90% of men with generalized lymphadenopathy had antibody to HTLV-III, while 21% of the controls were positive (p less than 0.001). Six patients with generalized lymphadenopathy developed the acquired immunodeficiency syndrome over 2 years; all were seropositive for HTLV-III. Thirty-six asymptomatic controls had had sexual contact with a man with the syndrome; receptive anal intercourse in this group was associated with seropositivity for HTLV-III. These data suggest that persistent generalized lymphadenopathy and the acquired immunodeficiency syndrome are part of a clinical spectrum of HTLV-III infection and that most high-risk homosexual men in some regions of the United States have not yet been infected with this virus.

Acquired Immunodeficiency Syndrome↗
PubMed1983

New concepts in medical bacteriology.

Traditional tests employed in a clinical microbiology laboratory for speciation of bacteria rely upon the presence of one or more gene products (biochemical profile) from a population of bacterial cells. These traits have been stable over a relatively long period of time, and the techniques have served us well. Current technology allows for modification and potential improvement of this system. By chemically separating DNA strands and employing recombinant DNA techniques, direct identification of bacteria becomes possible. These methods can be adapted directly to the clinical setting. In addition, specific gene products yield clinical disease; monoclonal antibodies directed against these products may speciate a bacterium indirectly through a unique gene product. Specific gene products also provide markers for epidemiologic investigation. All these technologies should find frequent clinical application in the next several years. The discoveries a century ago that germs cause infection and that different germs cause different infections prompted the development of a system of taxonomy for pathogenic microbes. It then became apparent that the identity of the germ infecting a patient could tell us more about his or her diagnosis and prognosis than could all of the clinical skills accumulated up to that time.

Anti-Bacterial Agents↗
PubMed1976

Epidemiologic findings on the relationship of time of day and time since last meal to glucose tolerance.

Data from 10,559 men and women, age 30-64, participating in the morning and afternoon in a Chicago Health Department multiphasic screening project, were used to determine the effects of time of day and time since last meal on the values for plasma glucose one and two hours following oral challenge with 100 gm. of glucose. Mean plasma glucose values and rates of suspect glucose intolerance (based on several cutpoints) were sizeably higher in the afternoon than in the morning. In addition, plasma glucose values increased with time elapsed since the last meal, up to 10 hours postprandially. Thereafter, both one- and two-hour plasma glucose values tended to exhibit a decline. Analysis of covariance confirmed that fluctuations in glucose tolerance were related to time of day and time since last meal, but the effects of each parameter were exerted independently.

Adult↗
PubMedDate not supplied

HIV-positive women: reasons they are tested for HIV and their clinical characteristics on entry into the health care system.

STUDY OBJECTIVE: To describe the reasons for the HIV testing of HIV-positive women and their clinical presentation and to make specific laboratory comparisons between women intravenous drug users (IVDUs) and non-IVDUs who were heterosexually infected (HTs). DESIGN: Consecutive case series. SETTING: Four primary care sites associated with the Brown University AIDS Program. PARTICIPANTS: 140 consecutive HIV-seropositive women. RESULTS: The most common reason for HIV testing in both groups was self-perception of risk. Presenting T-helper lymphocyte counts, leukocyte counts, and hematocrits did not differ significantly between the groups. Intravenous drug users were significantly more likely than HTs to have evidence of hepatitis B virus exposure (p less than 0.0001) and to report the history of a sexually transmitted disease (p = 0.005). Twenty percent of HTs versus 10% of IVDUs were tested only after they had HIV-related symptoms. The most frequent clinical presentation for both groups was Centers for Disease Control Group IV/A constitutional symptoms. CONCLUSIONS: Many HIV-seropositive women do not enter the health care system until they are symptomatic, but those infected heterosexually and those using parenteral drugs have similar laboratory indices at presentation. AIDS education strategies toward all women at risk must include information about manifestations of HIV disease in women, as well as preventive measures, to ensure early access to the health care system.

AIDS Serodiagnosis↗