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Biomedical subjects

K Gregory

Publications and source records attributed to K Gregory.

At least 19 recordsLinked to original sources
PubMed1996

Periodontal status of diabetic and non-diabetic men: effects of smoking, glycemic control, and socioeconomic factors.

Periodontal disease is more prevalent and more severe in diabetic than in non-diabetic individuals but the magnitude of this increase is still being debated. This prospective, cross-sectional study compared the periodontal status of 118 diabetic men and 115 age-matched non-diabetic men. Plaque and gingival indices, bleeding scores, probing depth, loss of attachment, and number of missing teeth were measured in a blinded manner. Smoking status, glycemic control, socioeconomic status, and previous dental care were also assessed. These parameters were significantly higher in diabetic than non-diabetic men: plaque index, P < 0.0001; gingival index, P < 0.0002; bleeding score, P < 0.0001; probing depth, P = 0.0059; loss of attachment, P < 0.0001; and missing teeth, P < 0.005. These parameters were significantly higher in smokers than non-smokers: gingival index, probing depth, and loss of attachment. The duration of diabetes was not significantly related to the periodontal measures. Glycemic control as assessed by fasting plasma glucose and glycohemoglobin values was not significantly correlated to periodontal status. These studies indicate, for this study group, that diabetes significantly affects all measured parameters of periodontal status.

Adult↗
PubMed1995

The outcome of macrosomic infants weighing at least 4500 grams: Los Angeles County + University of Southern California experience.

OBJECTIVE: To describe the maternal and neonatal outcome of macrosomic infants weighing at least 4500 g. METHODS: Maternal and neonatal records of infants with birth weights of at least 4500 g were identified during 1991. Outcome variables included the mode of delivery and incidence of maternal and perinatal complications. RESULTS: The study sample consisted of 227 infant and mother pairs. Mean (+/- standard deviation) birth weight was 4706 +/- 219 g. A trial of labor was allowed in 192 women, and elective cesarean delivery was performed in 35 patients. The overall cesarean rate, including elective cesarean delivery and failed trial of labor, was 30.8% (70 of 227). Of those undergoing a trial of labor, 82% (157) delivered vaginally. Shoulder dystocia occurred 29 times, for an incidence of 18.5% in vaginal deliveries for macrosomia. There were seven cases each of Erb palsy and clavicular fracture, and one humeral fracture. By 2 months of age, all affected infants were without permanent sequelae. There was no birth asphyxia or perinatal mortality related to delivery for macrosomia. Maternal complications included increased risk of lacerations requiring repair (especially third- or fourth-degree lacerations) when vaginal delivery was complicated by shoulder dystocia (relative risk [RR] 5.4, 95% confidence interval [CI] 3.1-9.4). There was no statistically significant difference with respect to hemorrhage or hospital stay for women who had a vaginal delivery (with or without shoulder dystocia) compared with women who had a cesarean delivery. However, infectious morbidity increased significantly in those patients who underwent a cesarean after a trial of labor compared with women who had a vaginal delivery (RR 7.1, 95% CI 3.9-13.1) or elective cesarean birth (RR 5.4, 95% CI 3.1-9.4). Ninety-one percent of patients undergoing elective cesarean delivery had no complications. CONCLUSION: Vaginal delivery is a reasonable alternative to elective cesarean for infants with estimated birth weights of at least 4500 g, and a trial of labor can be offered.

Adolescent↗
PubMed1995

An identified glutamatergic interneuron patterns feeding motor activity via both excitation and inhibition.

1. Previously we demonstrated that glutamate is an important neurotransmitter in the CNS of Helisoma. Exogenous glutamate applied to the buccal ganglia mimicked both the excitatory and inhibitory effects of subunit 2 (S2) of the tripartite central pattern generator (CPG) on S2 postsynaptic motor neurons. Here we identify buccal interneuron B2 as an S2 interneuron by utilizing a combination of electrophysiology, pharmacology, and intracellular staining. In addition, neurons that were electrophysiologically and morphologically characterized as neuron B2 demonstrated antiglutamate immunoreactivity, suggesting that neuron B2 is a source of endogenous glutamate in the buccal ganglia. 2. Depolarization of neuron B2 evoked excitatory postsynaptic potentials in motor neurons excited by S2. The excitatory effects of B2 depolarization and S2 activation were reversibly antagonized by the ionotropic glutamate receptor antagonist 6-cyano-7-nitro-quinoxaline-2,3-dione, similar to the antagonism shown previously for application of exogenous glutamate. Depolarization of neuron B2 also evoked inhibitory postsynaptic potentials in motor neurons inhibited by S2. When such motor neurons were maintained in isolated cell culture, application of exogenous glutamate produced a direct hyperpolarization of the membrane potential. 3. The activity of neuron B2 is necessary for the production of the standard pattern of buccal motor neuron activity, which underlies functional feeding movements. The subunits of the tripartite buccal CPG must be active in the temporal sequence S1-S2-S3 to produce the standard feeding pattern. Rhythmic inhibition from neuron B2 terminated activity in S1 postsynaptic motor neurons and entrained the frequency of activity in S3 postsynaptic motor neurons. Hyperpolarization of neuron B2 disrupted the production of the standard motor pattern by eliminating S2 postsynaptic potentials in identified buccal motor neurons, thereby prolonging S1 activity and disrupting S3 bursting. 4. These data support the hypothesis that S2 neuron B2 is glutamatergic and demonstrate that glutamatergic transmission, and especially inhibition, is fundamental to the production of behaviorally critical motor neuron activity patterns in Helisoma.

6-Cyano-7-nitroquinoxaline-2,3-dione↗
PubMed1993

Relaxation of vascular smooth muscle induced by low-power laser radiation.

The relaxation of rabbit aorta rings induced by low-power laser radiation was investigated in vitro to determine the location of the chromophore(s) responsible for this response and evaluate possible mechanisms. An action spectrum for relaxation was measured on rabbit thoracic aorta rings precontracted with norepinephrine. The decrease in isometric tension was measured during exposure to laser light (351-625 nm) delivered via a fiber optic to a small spot on the adventitial surface. The shortest UV wavelength (351 nm) was 35-fold more effective than 390 nm and 1700-fold more effective than 460 nm. Ultraviolet wavelengths also produced greater maximum relaxation (0.40-0.45) than visible wavelengths (0.20-0.25), suggesting that photovasorelaxation involves more than one chromophore. The adventitial layer was not necessary for photovasorelaxation, indicating that the light is absorbed by a chromophore in the medial layer. The same degree of relaxation was obtained on rings without adventitia when either one-half of the ring, or a small spot was irradiated indicating that communication between smooth muscle cells spreads a signal from the area illuminated to the entire ring. The mechanism for photovasorelaxation was investigated using potential inhibitors. N-monomethyl-L-arginine and N-amino-L-arginine, inhibitors of nitric oxide synthase, did not alter photovasorelaxation nor did indomethacin, an inhibitor of cyclooxygenase, and zinc protoporphyrin, an inhibitor of heme oxygenase.

Animals↗
PubMed1993

Evaluation of routine diabetes and lipid screening after age 35 in candidates for or current users of oral contraceptives.

OBJECTIVE: To evaluate the efficacy of a diabetes and lipid screening program in women aged 35 or older who either were currently using a low-estrogen-dose oral contraceptive (OC) (0.03-0.04 ethinyl estradiol) or who desired to initiate low-dose OC therapy after using a non-OC method or following a recent pregnancy. METHODS: Healthy women with no history of abnormal glucose tolerance, hypertension, or hyperlipidemia aged 35 years and older were routinely screened for diabetes (fasting and 2-hour values after 75 g glucose) and dyslipidemia (fasting total cholesterol, high-density lipoprotein [HDL] and low-density lipoprotein [LDL] cholesterol, and triglycerides). Three groups of women were studied: women currently using low-dose OCs (OC group), women desiring to change to OC therapy (non-OC group), and women within 3 months post-pregnancy (postpartum group). RESULTS: The three groups were similar in age, parity, body mass index (BMI), and mean arterial pressure. The mean months of contraceptive use were not different between the OC group (30.2 months; 95% confidence interval [CI] 26.6-33.8) and the non-OC group (38.4 months; 95% CI 32.0-44.8). The mean fasting serum glucose, after adjusting for age and BMI, was significantly lower in the OC group (82.4 +/- 9.4 mg/dL) than in the non-OC and postpartum groups (87.2 +/- 12.5 and 86.8 +/- 13.0 mg/dL, respectively; P = .01). After adjustments, no differences between the groups were found in the 2-hour post-glucose levels, triglycerides, or HDL or LDL cholesterol levels. The non-OC group was found to have a significantly lower total cholesterol level (188.7 +/- 32.4 mg/dL) than the OC and postpartum groups (202.7 +/- 38.1 and 204.4 +/- 41.0 mg/dL; P = .02) after adjusting for age and BMI. This association lost its significance after applying multiple range tests, maintaining an alpha error of 0.05. CONCLUSION: The absence of significant adverse metabolic markers in longer-term OC users over the age of 35, in comparison to similar-age control groups, does not support the routine use of lipid and diabetes screening before initiating or during the use of low-dose OCs.

Adult↗
PubMed1992

Removal of retained intrauterine contraceptive devices in pregnancy.

Using real-time ultrasound and clinical expertise gained from chorionic villus sampling, we describe a technique for ultrasound-guided intrauterine device removal in those cases in which the string is not visible. Utilizing a stone clamp for intrauterine manipulation, we were easily able to extract the device without interrupting the pregnancy. We concur with recent recommendations advocating all intrauterine devices can be removed if pregnancy termination is declined.

Adult↗
PubMed1991

Optical coherence tomography.

A technique called optical coherence tomography (OCT) has been developed for noninvasive cross-sectional imaging in biological systems. OCT uses low-coherence interferometry to produce a two-dimensional image of optical scattering from internal tissue microstructures in a way that is analogous to ultrasonic pulse-echo imaging. OCT has longitudinal and lateral spatial resolutions of a few micrometers and can detect reflected signals as small as approximately 10(-10) of the incident optical power. Tomographic imaging is demonstrated in vitro in the peripapillary area of the retina and in the coronary artery, two clinically relevant examples that are representative of transparent and turbid media, respectively.

Coronary Disease↗
PubMed1990

Beyond drug effects and dependent variables: the use of the Poisson-Erlang model to assess the effects of D-amphetamine on information processing.

Several studies have shown that d-amphetamine (DAMP) speeds mean reaction time (RT). However, the use of mean RT may obscure important aspects of the drug response. Therefore we applied the Poisson-Erlang (PE) stochastic model of choice reaction time proposed by Pieters (1985) to the RT distribution. This model proposes that the RT distribution is generated by two states: Processing (P) and Distraction (D). RT represents the sum of the time spent in each of these states. P is the time taken to complete a set of cognitive operations which are required to give a correct response. D represents the time taken by all other activities. RTs were collected using a task (SERS) in which stimulus and response complexity each had two levels, easy and hard. Subjects were tested pre- and postdrug. Drug conditions were: placebo, 10 mg d-amphetamine (DAMP), 4 mg of the dopamine agonist, pimozide, and a combination of DAMP and pimozide (COMBO). Parameters of the model were derived using methods described by Pieters. Four measures were analyzed: Processing Time (PT); Mean Time per distraction (XTD); Distraction Rate (DR); and Total Distraction Time per trial (TDT). Mean RT is also presented. Analyses of the effects of task conditions on the parameters of the model were made using the predrug sessions. Mean RT was increased by both stimulus and response complexities as was PT. TDT was increased by the task conditions. The PE measures did not change over days. DAMP speeded mean RT. However, this effect did not interact with the task factors. DAMP speeded processing and reduced distraction. Processing was speeded only in the hard response condition, distraction time was reduced only in the easy response condition. The results indicate that the PE model can be successfully applied to fast RT tasks. More importantly, the parameters of the model revealed important pharmacological effects that were not apparent in mean RT. DAMP speeds cognitive operations related to motor preparation and reduces the effects of distraction. Consistent with past studies there are no indications that DAMP interacted with stimulus processing. The distraction effect appears to be mediated by an increase in the rate of distraction and a decrease in the average time of these distractions.

Adult↗
PubMed1990

Self-generated mnemonics for enhancing free recall performance in older learners.

The effectiveness of self-generated mnemonic strategies for free-recall list learning was examined in 94 older community-dwelling adults. Participants were presented with a list of 19 nouns and were given seven minutes to commit the list to memory with three minutes for recall. Performance was measured immediately following recall and after a 2-day delay. Forty-five percent of the participants reported using a specific organizational mnemonic encoding strategy to facilitate recall. At both immediate and delayed recall, those individuals who reported using a well-articulated mnemonic outperformed those reporting the use of repetition or making simple associations. The results suggest that many older adults can spontaneously generate specific elaborative encoding strategies and that pre-existing encoding skills should be assessed prior to remedial memory training for older adults.

Aged↗
PubMed1987

Medical students' expectations for encounters with minority and nonminority patients.

The authors examined the expectations of firstyear medical students (n = 139) at the University of California, Los Angeles, School of Medicine in regard to interacting with black, Latino, Asian, and white patients. Using slides and a questionnaire, the results indicated that students expected to be significantly less comfortable interviewing blacks than other patients and to view blacks and Latinos as less likely to comply with treatment than whites and Asians. Black and Hispanic students were significantly more likely than white and Asian students to expect black and Hispanic patients to comply with treatment.

Adolescent↗
PubMed1986

Which first-year medical students expect to practice in an inner-city or ghetto setting.

The authors examined the expected practice location of first-year medical students at UCLA School of Medicine using self-administered questionnaires. The response rate was 94 percent. About 24 percent of students are from underserved minority groups. Compared with nonminority students, minority students are significantly older, of lower socioeconomic status, and more likely to have been raised in an inner-city or ghetto environment (each P<.05). While the average nonminority student expected to practice in a noninner-city, urban, or suburban environment, the average minority student expected to practice in an inner-city or ghetto environment (P<.0001). Differences in expected practice location due to ethnicity remained after controlling for sociodemographic factors. Students with previous medical experience and those from poorer sociodemographic backgrounds are also more likely to expect to practice in ghetto environments, regardless of ethnic background (each P<.05).

Adult↗