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Biomedical subjects

C Graham

Publications and source records attributed to C Graham.

At least 19 recordsLinked to original sources
PubMed1992

ELF exposure facility for human testing.

A laboratory facility specifically designed for controlled human exposure to 60-Hz electric (0 to 16 kV/m) and magnetic (0 to 32 A/m, B = 0 to 40 microT) fields has been constructed. The facility presents uniform fields under controlled temperature and humidity. Special control systems allow collection of physiological data during, as well as before and after, exposure to electric fields at strengths to 16 kV/m under verified double-blind control. Exposure to continuous or intermittent fields is possible in the facility. The capability of obtaining physiological data during actual exposure to constant or intermittent, 60-Hz fields, and of doing so without either the subject or the experimenter being aware of actual field conditions, is a critical factor in valid experimentation.

Electromagnetic Fields↗
PubMed1992

A replication study of human exposure to 60-Hz fields: effects on neurobehavioral measures.

The purpose of this study was to reproduce and extend an earlier investigation of the effects of human exposure to combined, 60-Hz electric and magnetic fields. This paper presents the neurobehavioral results. Thirty men participated in one training session and four testing sessions. Subjects were randomly assigned to two groups. The 18 subjects in Group I were exposed (9 kV/m, 20 microT) and sham exposed in two counterbalanced orders. In Group II, half of 12 subjects were exposed (9 kV/m, 20 microT) every session, and the remaining half were sham exposed every session. The study was doubly blinded. Measures of cardiac interbeat interval, event-related brain potentials, and performance were obtained before, during, and after exposures. As in the earlier study, exposure to the combined field resulted in a statistically significant slowing of heart rate, in changes in late components of event-related brain potentials, and in decreased errors on a choice reaction-time task. In addition, field effects on several other measures approached statistical significance. The physiological measures obtained during exposure indicated that effects were greatest soon after the field was switched on, and again when it was switched off. The data indicate that changes in exposure level may be more important than duration of exposure for producing effects in human beings.

Adult↗
PubMed1992

Influences of exogenous epinephrine on two reproductive parameters in female mice: disruption of receptivity but not implantation.

Diverse stressors impede female receptivity and fertility. Since epinephrine is released from the adrenal during stress, it might play a role in stress-induced disruptions of female reproductive parameters. Experiment 1 examined whether exogenous epinephrine would disrupt lordosis behavior in estrogen- and progesterone-treated ovariectomized female mice. Single dosages of 20 and 40 micrograms almost eliminated sexual receptivity. Experiments 2 and 3 examined whether chronic dosages of epinephrine shortly after insemination would lead to a failure of implantation of mouse embryos. Results indicated that epinephrine had little effect on the number of dams delivering pups, the number of pups born, litter weight, or the number of stillbirths.

Aggression↗
PubMed1992

A study of coroner's records of suicide in young people, 1986-88 in Western Australia.

Coroner's records of 25 consecutive suicides aged 15-19 years and 43 aged 20-24 years were compared with 68 suicides aged 45-59 years to identify associated clinical and psychosocial factors. Male: female ratios were 2.6:1, 5.1:1 and 3.5:1 respectively. The most common method of suicide in males in all three age groups was CO poisoning using motor vehicles. In females the teenage group used mainly active methods, whilst in the 20-24 and 45-49 years age groups the most common method was overdosage. Over 90% of each age group had some identifiable psychiatric symptomatology. In each age group the commonest symptoms were minor affective symptoms. In each group the pattern was mainly of associated multiple rather than single psychosocial factors. In each group disruption of interpersonal relationships (boy-girlfriend, de facto, marital, family) was the predominant stressor. Compared with the 45-59 year group the following associated factors were significantly greater in (a) 15-19 years: personality/conduct disorders, unemployment and legal/disciplinary problems, and (b) 20-24 years: drug abuse and unemployment. Although the two younger groups had significantly more unemployment than the older group, only the 20-24 years group had significantly more unemployment compared with community age norms. Preventive implications of the findings are discussed.

Adolescent↗
PubMed1992

Analysis of four diverse population groups indicates that a subset of cystic fibrosis mutations occur in common among Caucasians.

To determine the nature and frequency of non-delta F508 cystic fibrosis (CF) mutations among diverse populations, we have sequenced exons 9-12 and 19-23 of the CF transmembrane conductance regulator (CFTR) gene from 128 CF chromosomes (39 U.S. Caucasian, 27 African-American, 42 Northern Irish, and 20 Israeli chromosomes). These regions were chosen because they encode the two putative ATP-binding folds of CFTR, domains which appear to have functional significance. In addition, CFTR exons 1 and 2 were analyzed in the American patients. Mutations were found on 49 of the 128 CF chromosomes. Nineteen different mutations were observed; six were novel, while the remaining 13 had been reported previously by our group or by other investigators. Six of nine different mutations found in African-American patients were unique to that population. However, the vast majority of the mutations found in U.S. Caucasians (eight of nine), Northern Irish (four of five), and Israelis (three of three) also occurred in other Caucasian groups. The preponderance of previously reported mutations in these three groups suggested that a subset of the non-delta F508 mutations occur in common among Caucasians. A survey of mutation frequencies in other Caucasian groups confirmed this observation. Unfortunately, this subset accounts for less than half of non-delta F508 CF mutations in most groups. These data suggest that screening for delta F508 and this select group of mutations will efficiently and economically maximize the number of CF mutations identified in Caucasian groups. However, it will be difficult to detect more than 90% of mutant CFTR alleles except in ethnically and geographically discrete populations where CF is the result of founder effect.

Amino Acid Sequence↗
PubMed1991

Characterization of the aldose reductase-encoding gene family in rat.

Although the enzyme aldose reductase (AR) is implicated in the development of tissue pathology in diabetes, the exact mechanism of this involvement remains unclear. To better understand the role that expression of the aldose reductase-encoding gene (ALR) may play in diabetic complications, we have begun to analyze the gene and its regulatory regions, and we present here the sequence of four ALR genes in the rat. The putative functional gene is 14.1 kb long, has ten exons which show perfect sequence identity to the rat lens AR RNA sequence, and nine introns with classical splice-site consensus sequences. Potential regulatory elements in the 5'-flanking region of this gene include a TATA box and two CCAAT boxes. Probing rat genomic Southern blots with a fragment from the first intron indicates that there is probably only one copy of this gene in the rat genome. The other three genes are processed pseudogenes which show approx. 90% identity to the rat lens AR RNA sequence, contain no introns, and have poly(A) regions at their 3' ends. Chromosomal localization studies show the presence of ALR genes on chromosomes 3, 4 and 6 in the rat with the putative functional gene mapped on chromosome 4.

Aldehyde Reductase↗
PubMed1991

Effects of methanol vapor on human neurobehavioral measures.

Methanol could become an important motor fuel. The objective of this exploratory study was to provide preliminary information about whether or not acute exposure to methanol at 250 mg/m3 for 75 minutes would have adverse effects on human neurobehavioral functions important in everyday life. This concentration level was selected because it is at the upper limit of the traffic scenario estimates provided by the U.S. Environmental Protection Agency (EPA)2 (86 to 240 mg/m3), but is below the maximum concentrations for eight-hour average exposures currently recommended by the National Institute of Occupational Safety and Health (NIOSH) and the American Conference of Government and Industrial Hygienists (ACGIH) (260 mg/m3). Although traffic scenario exposure estimates suggest that such high levels of exposure last less than 15 minutes, we used a 75-minute exposure to increase the probability of identifying dependent measures that should be studied in more detail in a future confirmatory study. Twelve healthy young men, each serving as his own control, participated in two sham exposures and two methanol exposures under counterbalanced, double-blind control conditions. Because methanol is present in many foods, and because high preexposure levels of methanol or formate might obscure exposure effects, subjects were required to strictly limit their diets for 12 hours before each experimental session. The following endpoints were examined before, during, and after exposure to methanol and sham vapors: blood and urinary methanol; plasma formate; oral temperature; blood pressure; subjective mood, alertness, fatigue, workload, and symptom scales; spectral analysis of the electroencephalogram; visual- and auditory-event-related potentials; contingent negative variation; respiration; cardiac interbeat interval; Symbol Digit substitution task; three-choice reaction time; Stroop color-word test; simple reaction time; visual function; critical flicker fusion frequency; hand steadiness; visual search task; Gamberale reaction time task; visual tracking task; Sternberg memory task; interval production task; and speeded addition task. Two dual tasks were also included in the task batteries. These endpoints were selected from those indicated in the literature to be sensitive to solvents, and from those that are widely used in other neurobehavioral test batteries to identify the effects of environmental pollutants. Because the number of endpoints examined was large and the number of subjects was small, procedures designed to reduce the number of statistical tests performed were used. Mean methanol concentration in the exposure room during methanol exposures was 249 mg/m3 (SD +/- 7 mg/m3). Exposure produced significant increases in blood and urine methanol concentration. As expected, no changes in plasma formate were observed.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1989

A superfamily of NADPH-dependent reductases in eukaryotes and prokaryotes.

Aldose reductase (AR) is implicated in some of the disabling complications of diabetes, including neuropathy, retinopathy and cataracts. Our studies are aimed at further clarifying the role of AR in diabetes and facilitating the design of new classes of potent, specific AR inhibitors by gaining an understanding of the protein structure of AR. To this end, we have determined the complete protein sequence of rat lens AR using cDNA analysis and primer extension of mRNA. By comparing protein sequences, we have found that the structural relatedness (41% to 57%) among the vertebrate proteins, aldose reductase, aldehyde reductase, prostaglandin F synthase and the frog lens protein rho-crystallin can now be extended to prokaryotes by the inclusion of Corynebacterium 2,5-diketo-D-gluconate reductase. This more distantly related protein shares 30-40% identity with the vertebrate enzymes. Sequence alignments reveal that 18% of the amino acids are completely conserved in all members of the superfamily, many of them in clusters, suggesting that they mark important structural features such as the nucleotide binding site and substrate binding site. rho-Crystallin, which is structurally related to this superfamily of NADPH-dependent reductases, does not appear to reduce PGH2, PGD2, xylose or glyceraldehyde to any appreciable extent. It does, however, bind NADPH.

Aldehyde Oxidoreductases↗
PubMed1975

Conservation of human research teeth by controlling cavity depth.

In order for the dental profession to obtain reliable data as to whether new or experimental restorative materials and adjunct agents are more or less irritating to pulp tissues than dental products currently in use, pulp studies at the national and international level are being standardized to enhance corroboration. The purpose of this study was to reduce the number of human teeth required in any experimental pulp toxicity study by controlling the problem of cavity depth. Many valuable teeth are wasted by making cavity preparations that are either too shallow or too deep, with consequent pulp exposures. This needs to be corrected.

Dental Cavity Preparation↗
PubMedDate not supplied

Diazepam and lorazepam for intravenous surgical premedication.

Diazepam, 10 and 20 mg, and 2 and 4 mg lorazepam were studied as intravenous surgical premedicants in 120 patients. Relief of anxiety, sedation, patient acceptance, lack of recall, and side effects were the variables evaluated. Both diazepam and lorazepam proved to be excellent surgical premedicants. The basic difference between the two drugs is temporal. Both medications produce similar relief of anxiety, sedation, patient acceptance, and lack of recall. The clinical effects of intravenous diazepam peaks in 2 to 3 minutes and diminishes thereafter. Intravenous lorazepam has a latent period of 8 to 15 minutes, with increasing effects at 15 to 30 minutes.

Adolescent↗
PubMedDate not supplied

Rehabilitation of a paraplegic prisoner: conflicts for patient and nurses.

The most frequent outcome of a physical rehabilitation program is discharge to an independent or assisted-living environment in the community. When a patient remains incarcerated throughout a rehabilitation stay and is returned to a prison at discharge, both patient and nurse can experience conflicts caused by differences in the two settings. This article presents a case study in which conflicts that occurred and strategies for their resolution are discussed.

Adult↗
PubMedDate not supplied

Pulmonary artery dissection: MR findings.

We report a case of pulmonary artery dissection imaged by MR. Dissection of a markedly dilated pulmonary artery is a rare and usually fatal complication of chronic pulmonary arterial hypertension. The diagnosis is made at autopsy, with only two cases having previously been documented (by Doppler echocardiography) during life. The hallmark of an arterial dissection is the finding of an intimal flap and a false lumen. In our case, spin echo MR imaging failed to show either the intimal flap or any intraluminal signal defects. The dissection was presumably obscured by nonhomogeneous intraluminal signal caused by the slow blood flow associated with severe pulmonary arterial hypertension. Cine MR imaging, however, demonstrated different signal intensity within the true and false lumens of the dissection, thereby outlining the intimal flap between the two channels.

Adult↗