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G Myers

Publications and source records attributed to G Myers.

At least 19 recordsLinked to original sources
PubMed1992

AIDS origin.

Explore the source record for details and available documents.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Molecular epidemiology of HIV transmission in a dental practice.

Human immunodeficiency virus type 1 (HIV-1) transmission from infected patients to health-care workers has been well documented, but transmission from an infected health-care worker to a patient has not been reported. After identification of an acquired immunodeficiency syndrome (AIDS) patient who had no known risk factors for HIV infection but who had undergone an invasive procedure performed by a dentist with AIDS, six other patients of this dentist were found to be HIV-infected. Molecular biologic studies were conducted to complement the epidemiologic investigation. Portions of the HIV proviral envelope gene from each of the seven patients, the dentist, and 35 HIV-infected persons from the local geographic area were amplified by polymerase chain reaction and sequenced. Three separate comparative genetic analyses--genetic distance measurements, phylogenetic tree analysis, and amino acid signature pattern analysis--showed that the viruses from the dentist and five dental patients were closely related. These data, together with the epidemiologic investigation, indicated that these patients became infected with HIV while receiving care from a dentist with AIDS.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Transmission of human immunodeficiency virus in a dental practice.

OBJECTIVE: To determine if patients of a dentist with the acquired immunodeficiency syndrome (AIDS) became infected with human immunodeficiency virus (HIV) during their dental care and, if so, to identify possible mechanisms of transmission. DESIGN: Retrospective epidemiologic follow-up of the dentist, his office practice, and his former patients. SETTING: The practice of a dentist with AIDS in Florida. PARTICIPANTS: A dentist with AIDS, his health care providers and employees, and former patients of the dentist, including eight HIV-infected patients. MEASUREMENTS: Identification of risks for HIV transmission (if present), degree of genetic relatedness of the viruses, and identification of infection control and other office practices. RESULTS: Five of the eight HIV-infected patients had no confirmed exposures to HIV other than the dental practice and were infected with HIV strains that were closely related to those of the dentist. Each of the five had invasive dental procedures, done by the dentist after he was diagnosed with AIDS. Four of these five patients shared visit days (P greater than 0.2). Breaches in infection control and other dental office practices to explain these transmissions could not be identified. CONCLUSION: Although the specific incident that resulted in HIV transmission to these patients remains uncertain, the epidemiologic evidence supports direct dentist-to-patient transmission rather than a patient-to-patient route.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Problems in measuring heart rate variability of patients with congestive heart failure.

Heart rate variability (HRV) has become an important noninvasive measure of the integrity of the autonomic nervous system in various disease states. The power spectrum of HRV is a means to separate the instability oscillations of the various feedback mechanisms that contribute to cardiovascular homeostasis. The reliability of HRV data is largely unexplored. The day-to-day correlations in the low and mid-frequency components of HRV spectra average 91%, and that of the high-frequency component averages 81%. The correlations among spectral and nonspectral measures of HRV (SD) for the same data segment average 50-60%, suggesting that they encode similar information. Heart rate variability spectra exhibit diurnal variation consistent with physiologic expectation: respiratory sinus arrhythmia (thought to be mediated by parasympathetic tone) and to a lesser extent, the low-frequency spectral component (thought to be of mixed sympathetic-parasympathetic origin) are higher at night than in the daytime; the mid-frequency component (associated with the baroreflex, which is more excited when the patient is upright) is slightly higher during the daytime. Increased frequency of ectopic beats, such as occurs in congestive heart failure, reduces the reliability of the power spectrum since the number of usable data segments falls off rapidly with even small increases in rate of ectopy, and the variance of the estimate (in the method of averaged periodograms) is inversely proportional to the square root of the number of data segments. Using shorter data segments increases the number of segments available, but reduces resolution. Interpolation over ectopic beats (by either linear or cubic splint interpolation) increases the apparent power in low frequencies.(ABSTRACT TRUNCATED AT 250 WORDS)

Electrocardiography↗
PubMed1992

Signature pattern analysis: a method for assessing viral sequence relatedness.

Signature pattern analysis identifies particular sites in amino acid or nucleic acid alignments of variable sequences that are distinctly representative of a query set of sequences relative to a background set. We explore the merits of using signature patterns for analysis of HIV-1 (human immunodeficiency virus type 1) sequences in cases of epidemiological linkage and potential superinfection. For these purposes, query sets are viral sequences that are all derived from one HIV-1 infected individual, hence the signature pattern is the array of sites that are characteristic of the range of viral variants obtained from that person. Once a signature pattern has been objectively defined, it can be used to examine other viral sequences from other individuals for evidence of genetic relatedness. A computer program to facilitate this analysis, VESPA, is described and applied to sequence data gathered during the investigation of HIV-1 transmission in a dental practice. The implications of signature polymorphisms seen within an infected individual, and shared polymorphisms between linked individuals, are also considered. VESPA may also be applied to the molecular analysis of biological phenotypes.

Amino Acid Sequence↗
PubMed1992

The emergence of simian/human immunodeficiency viruses.

Molecular evolutionary analyses strongly support the hypothesis that human immunodeficiency viruses have recently arisen from a diverse pool of nonhuman primate immunodeficiency viruses. Our understanding of the molecular phylogenetic relationships between primate and nonprimate lentiviruses is less certain, partly because key intermediate forms are still to be discovered. DNA and protein sequence comparisons reveal uncanny dissimilarities, as well as similarities, among the genetic sequences of these complex retroviruses, thereby giving rise to the notion that primate lentiviruses are participants in "fast-forward" evolution.

DNA, Viral↗
PubMed1992

Clostridial septicemia in an urban hospital.

The records of 56 patients at an urban hospital who had positive blood cultures for clostridia were reviewed. Each patient was classified as immunologically normal or immunosuppressed. Data were collected on clinical history, type of clostridial bacteremia, physical and laboratory determinants of infection, therapeutic intervention, clinical course and outcome. Of the 56 patients, 22 were determined to be immunosuppressed. Among all 56 patients, 28 had a malignancy, usually gastrointestinal or hematologic in origin. Fever, leukocytosis and abdominal pain were common in both groups. Clostridial bacteremia almost always heralded clostridial septicemia. A gastrointestinal source of infection, particularly carcinoma of the colon or rectum or enterocolitis, was evident or presumed in 43 of the 56 patients. Clostridium perfringens was the most frequently isolated microorganism, but C. septicum was associated with more complications and a higher mortality rate. Septic complications and mortality were higher among the patients with immunosuppression.

Adolescent↗
PubMed1989

Molecular characterization of HIV-1 isolated from a serum collected in 1976: nucleotide sequence comparison to recent isolates and generation of hybrid HIV.

Human immunodeficiency virus type 1 (Z321 designate, HIV-1Z321), the oldest known HIV, was isolated from a serum sample collected in Zaire in 1976 and was molecularly cloned. Restriction enzyme analysis of unintegrated viral DNA revealed the presence of conserved restriction enzyme cleavage sites in the long terminal repeat sequences. Nucleotide sequence analysis of the 3' end of the viral DNA revealed a pattern similar to other HIV-1 isolates described. However, some of the common restriction sites present in other isolates were absent in HIV-1Z321. The extent of differences between HIV-1Z321 and recent isolates from North America and Zaire was 17.86-18.36% on the nucleotide sequence level and 26.5-33.2% difference in the predicted amino acid sequence in the envelope gene. Differences were also noted in 3'-orf (nef: according to HIV gene nomenclature; see Ref. 42) gene and U3 region of the long terminal repeat sequences of HIV-1Z321 and other isolates. Nucleotide sequence of a HIV-1 isolate, 12 years apart from the present isolates, will provide an important time calibration point for the evolutionary divergence of HIV isolates. Hybrid HIV was also generated by transfecting HIV-1Z321 and HIV-1HTLV-III viral DNAs into cells.

Amino Acid Sequence↗
PubMed1989

Laser angioplasty of totally occluded coronary arteries and vein grafts: preliminary report on a current trial.

CLINICAL PERSPECTIVE: Among the various laser angioplasty systems and atherectomy devices currently in clinical trials, the Lastac system appears to be particularly suitable for treating totally occluded coronary arteries and vein grafts. Preliminary results of a clinical trial in more than 35 patients show a recanalization rate of 92% and no complications attributable to the laser. Restenosis has occurred in five cases; in three of these, the arteries were reopened with laser or conventional angioplasty.

Angioplasty, Balloon↗
PubMed1988

The phylogenetic history of immunodeficiency viruses.

Knowledge of the phylogenetic history of the human immunodeficiency viruses (HIV-1 and HIV-2) is important for our understanding of the epidemiology of AIDS, the disease caused by these viruses. Reconstruction of the evolutionary tree is hampered, however, by two problems. One is the high variation in nucleotide sequence between the known HIV isolates which can create formidable difficulties in identifying homologous genomic sites that may be used in a molecular phylogenetic reconstruction. Another impediment has been the lack of unequivocal time calibration points: there is only a sparse 'fossil record' for HIV and limited historical epidemiological data. We have largely overcome these difficulties by: (1) a thorough optimal-sequence alignment analysis; (2) the inclusion of sequences of an early (1976) HIV-1 isolate, a recent (1986) HIV-2 isolate and two simian immunodeficiency viruses (SIV) along with five other HIV-1 isolates; and (3) the reconstruction of a minimum-length evolutionary tree based on the envelope-gene variable positions. We conclude that HIV-1 may have evolved from its common ancestor with HIV-2 as recently as 40 years ago.

Animals↗
PubMed1988

Patterns of substance use on a college campus: a 14-year comparison study.

In 1972, a drug incidence survey was conducted at a private southern university. Pooled results of this random survey of 1,032 students revealed that on at least one occasion, 90% of the students had tried alcohol, 70% had used tobacco, and 61% had experimented with marijuana. Use of amphetamines (38%), hallucinogens (28%), barbiturates (19%), and cocaine (10%) was much lower. To evaluate the apparent change in trends of drug usage, a follow-up study was undertaken in 1986 at the same school. The results showed a decline in amphetamine and barbiturate use. The greatest differences were seen in the nearly fourfold increase in one-time use of cocaine between 1972 and 1986 and the sixteenfold increase in students who used cocaine more than 10 times. It was noteworthy that one-third of the students who used marijuana had done so by the 9th grade. Similar early experimentation was noted with a majority of the other drugs.

Adult↗
PubMed1987

Symptomatic atlantoaxial dislocation in Down's syndrome.

Four patients with Down's syndrome suffered compression of the spinal cord secondary to atlantoaxial dislocation. All four developed inability to walk and quadriparesis, with signs of cervical myelopathy. It is important to recognize this potentially fatal complication of the syndrome. Immediate immobilization of the neck, followed by cervical roentgenograms, should be done in any patient with Down's syndrome who presents with neck pain, torticollis, urinary incontinence, or loss of ambulation. Surgical repair with fusion of the first and second cervical vertebrae can be carried out later.

Adolescent↗
PubMed1979

Early malfunction of transvenous pacemaker electrodes. A three-center study.

A 3-year study by three medical centers has revealed a 1-year electrode malfunction rate of 7.4%; most malfunctions occurred within the first 30 days. The incidence of unavoidable early malfunction (3.2%) fell within the 5% standards suggested by the committee report of the Inter-Society Committee on Heart Diseases. Incidences of obscure cause (3.2%) may be difficult to identify prospectively and may be, to a certain extent, unavoidable. The majority of the malfunctions (4.2%) showed specific clues that indicated that they were preventable. Successful repositioning was achieved on the first attempt in 80.6% of the cases with malfunction, and only 0.7% required ultimate myocardial electrode implantation. The principal clues to potentially unsatisfactory positioning included the presence of a large right ventricle with or without tricuspid insufficiency, current thresholds greater than 0.5 mA and ST-segment deviations on the intracardiac electrogram of less than 2 mV. Electrode malfunction may be more common with bipolar than with unipolar electrodes; but significant differences in the incidence of malfunction among different unipolar electrodes were observed. These data indicate that further developments in transvenous electrode design are warranted.

Arrhythmia, Sinus↗