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Biomedical subjects

L A Stevens

Publications and source records attributed to L A Stevens.

33 records · Page 2Linked to original sources
PubMed1993

Automated biopsy devices: a blinded evaluation.

To evaluate 20 different automated biopsy devices with respect to the quality of tissue obtained for histopathologic analysis, a total of 1,470 18-gauge biopsy specimens were obtained from 10 fresh autopsy cases, including 30 liver, 20 kidney, 10 pancreas, and 10 psoas muscle biopsy specimens per device and per biopsy depth. There was no statistical difference in the performance of the long-throw Biopty, ASAP 18, 1.9-cm UltraCut, long-throw Monopty, and 2.5-cm ABS biopsy guns. All obtained a large amount of tissue with minimal fragmentation or crush artifact. Most of the short-throw biopsy guns (depth of biopsy < or = 1.1 cm) did not perform as well. Although the other guns performed adequately, less than optimal results were obtained with the Temno, Bio-Gun, Roth, Klear Kut, ABC, and Urocut biopsy guns. Most 18-gauge automated biopsy devices with a biopsy excursion of at least 2.0 cm provide a high-quality, diagnostically adequate specimen for histopathologic analysis.

Biopsy, Needle↗
PubMed1993

Blinded comparison of biopsy needles and automated devices in vitro: 1. Biopsy of diffuse hepatic disease.

OBJECTIVE: The purpose of this study was to compare several of the commonly used needles with several of the new automated biopsy devices (biopsy guns) for biopsy of diffuse hepatic disease. MATERIALS AND METHODS: Nine different biopsy needles or automated devices were each used to do three biopsies of 10 cadaveric livers. The specimens were reviewed in a blinded fashion by a pathologist who did not know which needle or device was used, and they were compared on the basis of a previously published histopathologic grading scale. RESULTS: The three conventional biopsy needles (16-gauge Jamshidi, 18-gauge Sure-Cut, and 14-gauge Tru-Cut) obtained a large amount of tissue with an average of 4.1 intact portal triads per biopsy. The 18-gauge Biopty gun obtained equivalent results. The 18-gauge Autovac gun with a 2-cm biopsy depth did not obtain any tissue in 18.5% of attempts. The 14- and 16-gauge Biopty guns and the 18-gauge Autovac gun with a 4-cm biopsy depth performed best with respect to fragment size and number of intact portal triads. CONCLUSION: Automated biopsy devices can provide more diagnostic specimens than can manual or conventional needles in biopsy for diffuse hepatic disease.

Biopsy, Needle↗
PubMed1993

Blinded comparison of biopsy needles and automated devices in vitro: 2. Biopsy of medical renal disease.

OBJECTIVE: The purpose of this study was to compare several of the commonly used manual biopsy needles with several of the new automated biopsy devices (biopsy guns) for biopsy of medical renal disease. MATERIALS AND METHODS: Ten different biopsy needles or automated devices were each used to do two biopsies of 10 cadaveric kidneys. The specimens were reviewed in a blinded fashion by a pathologist using a previously published histopathologic scale. RESULTS: Of the four conventional biopsy needles tested (16-gauge Jamshidi, 18-gauge Sure-Cut, 14-gauge Tru-Cut, and 14-gauge Vim Silverman), the Jamshidi needle obtained the greatest average number of glomeruli (5.64). Results similar to those obtained with the conventional needles were obtained with the 16- and 18-gauge Biopty and Ultra-Cut biopsy guns. The 18-gauge Autovac gun with either a 2- or 4-cm depth of biopsy suffered from a significant number of biopsies from which no tissue was obtained. The 14-gauge Biopty gun was clearly superior, leading in all graded categories including the average number of glomeruli (8.11) per biopsy. CONCLUSION: The automated biopsy device, or biopsy gun, can provide more diagnostic specimens than can manual or conventional needles in biopsy for medical renal disease.

Biopsy, Needle↗
PubMed1992

Pertussis toxin-catalyzed ADP-ribosylation of G(o) alpha with mutations at the carboxyl terminus.

The guanine nucleotide-binding protein G(o alpha) has been implicated in the regulation of Ca2+ channels in neural tissues. Covalent modification of G(o alpha) by pertussis toxin-catalyzed ADP-ribosylation of a cysteine (position 351) four amino acids from the carboxyl terminus decouples G(o alpha) from receptor. To define the structural requirements for ADP-ribosylation, preparations of recombinant G(o alpha) with mutations within the five amino acids at the carboxyl terminus were evaluated for their ability to serve as pertussis toxin substrates. As expected, the mutant in which cysteine 351 was replaced by glycine (C351G) was not a toxin substrate. Other inactive mutants were G352D and L353 delta/Y354 delta. Mutations that had no significant effect on toxin-catalyzed ADP-ribosylation included G350D, G350R, Y354 delta, and L353V/Y354 delta. Less active mutants were L353G/Y354 delta, L353A/Y354 delta, and L353G. ADP-ribosylation of the active mutants, like that of wild-type G(o alpha), was enhanced by the beta gamma subunits of bovine transducin. It appears that three of the four terminal amino acids critically influence pertussis toxin-catalyzed ADP-ribosylation of G(o alpha).

Adenosine Diphosphate Ribose↗
PubMed1992

Fluvoxamine does not interact with alcohol or potentiate alcohol-related impairment of cognitive function.

OBJECTIVE: To assess whether fluvoxamine alters the pharmacokinetics of alcohol or potentiates alcohol-related impairment of cognitive function. METHODS: The study design required partially "blinded" balanced crossover studies, each involving 12 healthy male volunteers who each received a 40 gm dose of intravenous or oral alcohol after single and multiple doses of 50 mg fluvoxamine. Main outcome measures for pharmacokinetics were venous blood alcohol and plasma fluvoxamine. Main outcome measures for pharmacodynamics were word recall, simple and choice reaction time, number vigilance, memory scanning, and word recognition. RESULTS: The pharmacokinetics of intravenous alcohol were not affected by concomitant administration of fluvoxamine. Compared with placebo-alcohol, alcohol slightly increased the rate of fluvoxamine absorption, but the area under the plasma concentration-time curve from 0 to 12 hours at steady state was unchanged. As expected, alcohol significantly impaired cognitive function in volunteers. However, fluvoxamine did not potentiate the effects of alcohol and in some instances appeared to reverse the effects or reduce their duration. Fluvoxamine was well tolerated: only mild adverse effects were reported, and none of those required intervention. CONCLUSION: Fluvoxamine does not interact significantly with alcohol or potentiate alcohol-related impairment of cognitive function.

Administration, Oral↗
PubMed1990

An AIDS educational program for third-year medical students.

Medical student training now involves an increasing number of patients with HIV infection and AIDS. Thus far educational efforts to change attitudes and behaviors toward AIDS patients have not been successful. Education that only involves the presentation of information appears to be insufficient to alter fearful and prejudicial attitudes toward such patients. Using four different teaching modules (open discussion, role play, and two videotapes) we demonstrated a positive change in students' anticipation of how they would respond to a question or a statement from a non-AIDS patient or a patient with AIDS. There were significant changes in the students' response to AIDS patients on the Understanding, Probing, Focusing, and Judgmental scales of the Medical Helping Relationship Inventory. This initial work suggests that educators can have a positive effect on students' attitudes. Techniques that traverse the emotional barriers students erect to protect themselves from the painful feelings stimulated by working with AIDS appear to be useful.

Acquired Immunodeficiency Syndrome↗
PubMed1987

Techniques for reversing the failure of empathy towards AIDS patients.

Educating the general population and health care workers about the acquired immunodeficiency syndrome (AIDS) is of paramount importance. There is a need to address the many fears and anxieties concerning this dreaded illness. Experience has shown that simple information-giving alone does little to allay the panic in the general population and in hospital personnel. The paper offers a psychodynamic explanation of the origins of the irrational fear and anxieties around AIDS patients and why information alone does not help the anxieties hospital workers experience. We have suggested a training program using group process and videotape techniques which can address the underlying fears and concerns about AIDS patients. These sessions can help hospital staff to deliver more empathic care to this patient group.

Acquired Immunodeficiency Syndrome↗
PubMed1985

Correlation of the clinical pharmacodynamics of loprazolam with serum concentration.

Six healthy fasted volunteers each received oral doses of a placebo, 1 mg and 2 mg loprazolam with one week between treatments using a double-blind balanced crossover design. Serum samples were obtained at selected times after dosing for measurement of loprazolam using a combined high-performance liquid and gas chromatographic assay. Drug effect was also measured at the corresponding times using self-assessment scales and psychomotor tests. The serum levels of loprazolam followed a somewhat irregular shape with secondary and tertiary peaks possibly associated with food intake. The maximum serum levels of loprazolam following 1 mg and 2 mg doses of the drug (6.0 +/- 2.6 and 11.3 +/- 2.9 ng/ml, respectively) occurred at approximately one hour after dosing. Both the maximum serum levels and the area under the curve of loprazolam measured to six hours increased in direct proportion to dose. Statistically significant drug effects were seen after 2 mg loprazolam, although the subjects also appeared sedated after 1 mg doses. There appeared to be a good correlation between the logarithm of the serum concentration of loprazolam and effect which suggested that the hypnotic activity of the drug was not mediated via a long-lived metabolite. A threshold serum concentration associated with evident sedation was observed at approximately 3 ng/ml.

Adult↗
PubMed1984

Comparative bioavailability of two furosemide formulations in humans.

Twelve healthy male volunteers participated in a balanced crossover comparison of a brand-name and generic furosemide formulations. Each treatment was given as a single 40-mg tablet following an overnight fast. Furosemide concentrations in plasma and urine were determined up to 24 h after treatment; urine output and urinary sodium excretion were also measured. In comparison with the brand-name tablets, generic furosemide was significantly less bioavailable. Using a 95% confidence interval approach, generic furosemide gave up to 66% lower maximum furosemide plasma levels, up to 52% less area under the plasma level curve to infinite time, and up to 37% less urinary recovery of furosemide. Comparison of the effect of the two treatments was a less sensitive measurement of bioequivalence. Confidence intervals for differences in urinary output and sodium excretion over the period of maximum effect (0-4 h) were, however, asymmetrical, and pharmacodynamic differences between treatments were significant at the 10% level.

Adolescent↗
PubMed1984

Intravenous and oral administration of molsidomine, a pharmacodynamic and pharmacokinetic study.

In 12 healthy male volunteers, molsidomine 1, 2 and 4 mg i.v. increased resting heart rate and decreased systolic blood pressure, the latter still being affected after 8 hours. After single oral doses of 1 and 2 mg, systolic pressure tended to be reduced for 90 minutes and exercise heart rate tended to be increased. After oral treatment with 2 mg molsidomine three times daily for 1 week, the pharmacokinetic parameters and the effects on heart rate and blood pressure after the final dose were not different from those after the first dose. The terminal half-life was independent of dose and route of administration. Clearance and distribution volume were not dose-dependent. The bioavailability of a 2 mg oral dose of molsidomine was 44%. Inter-individual variation in heart rate, blood pressure and pharmacokinetics was observed.

Administration, Oral↗
PubMed1984

The psychological impact of immediate breast reconstruction for women with early breast cancer.

Twenty-five patients were evaluated, 13 who had immediate breast reconstruction and 12 who had delayed breast reconstruction for early breast cancer. Data were elicited about the psychological impact of the cancer, the mastectomy, and the reconstruction. Our results support the conclusion that immediate breast reconstruction is accompanied by a lower incidence of psychological morbidity postoperatively, and we recommend that immediate breast reconstruction be offered as an alternative to women with early breast cancer.

Adult↗
PubMed1984

Whole body autoradiographic and quantitative tissue distribution studies with 14C-cefotaxime in the rat.

The absorption, distribution and elimination of radioactivity following intravenous (i.v.) or intramuscular (i.m.) administration of 14C-cefotaxime (14C-HR 756) to the rat has been examined by qualitative and quantitative techniques. After i.v. and i.m. doses to male albino animals radioactivity was extensively distributed throughout the body and rapidly eliminated with a predominant half-life of approximately 30 to 40 min. Maximum plasma levels for the i.m. dose were reached within 20 min and approximately 85% of the dose was recovered from the urine (74%) and faeces (11%) within 8 h after dosing. In all quantitative studies 100 +/- 5% of the dose was recovered within 24 h. Whole body autoradiography studies showed good distribution of radioactivity from the blood into the tissues including lung, liver, kidney, heart, bone marrow and the gastrointestinal tract. Lowest levels were seen in the eye and brain. There was limited placental transfer of radioactivity in 14-day pregnant animals although by day 18 of the gestation period radioactivity was detected in the foetus but distribution into individual organs and tissues could not be seen. There was no evidence to show that retention of radioactivity in pigmented tissues had occurred nor was there any suggestion of accumulation of radioactivity in any organ or tissue as a consequence of multiple dosing with 14C-cefotaxime.

Animals↗
PubMed1983

Single and repeated dose kinetics of the hypnotic agent loprazolam in healthy volunteers.

The pharmacokinetics of loprazolam have been studied in eight healthy male volunteers after single and repeated 2 mg oral doses taken at night, for eight nights. The absorption and disposition of unchanged drug (HPLC-GC assay) and receptor active benzodiazepine-type materials (radioreceptor assay) were examined after the first and eighth dose. Maximum levels of approximately 10 ng ml-1 (range 3.6 to 15.5 ng ml-1) were reached within about 2.5 h after dosing. The post-peak levels declined in a single exponential fashion with an overall mean +/- SD half-life of 7.06 +/- 1.98 h and total areas under the curve ranging from 35.9 to 189.0 ng ml-1 h. There were no statistical differences between the values for the first and eighth doses. There was no evidence to suggest that significant accumulation of parent drug or receptor active benzodiazepine-type materials had occurred, and it is concluded that the kinetics of loprazolam would allow repeated daily doses of 2 mg.

Adult↗