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Biomedical subjects

R Henderson

Publications and source records attributed to R Henderson.

At least 109 records · Page 6Linked to original sources
PubMed1993

Attempted experimental modification of the postlaminectomy membrane by local instillation of recombinant tissue-plasminogen activator gel.

A prospective, randomized, blinded trial involving 25 adult mongrel dogs was performed to evaluate whether placement of a fat graft or local instillation of recombinant tissue-plasminogen activator gel (rt-PA) could modify the development of a postlaminectomy membrane. One component of the study involved the performance of a lumbar laminectomy and placement of gel rt-PA, free fat, or no tissue placement over the exposed dura mater. Three months later the animals were killed and sections of spine were removed en bloc, decalcified, and examined histologically. No significant differences were found in the degree of cellular fibrosis or heavy collagen production. A similar laminectomy at another lumbar level was also followed by gel rt-PA, free fat, or no tissue placement. Three months after surgery, surgery was performed again at this level immediately before death. There were no differences in the adhesiveness of the laminectomy membrane to dura mater or roots. It was concluded that the local instillation of gel rt-PA after laminectomy did not inhibit scar formation or scar adherence to the dura mater.

Adipose Tissue↗
PubMed1993

A prototype multidisciplinary cancer screening clinic for the military medical facility.

Optimal treatment of cancer depends upon early diagnosis. With an aging retiree and dependent population, cancer diagnosis and management must be addressed by military medical treatment facilities (MTFs) in a coherent and cost-effective fashion. A prototype multidisciplinary cancer screening clinic is described which interdigitated MTF and local American Cancer Society resources. Sites screened included breast, prostate, skin, cervix, and oral cavity, with mammograms, prostate-specific antigens, PAP smears, and physical exams, as appropriate. Of 194 patient contacts over a 4-hour period, eight cancers were found and subsequently treated (five skin, three prostate). Patient selection criteria, screening results by site, lessons learned, and recommendations for future clinics are discussed. The multidisciplinary screening clinic is readily applicable to the MTF setting, cost-effective, and provides an invaluable service to eligible patients.

Ambulatory Care Facilities↗
PubMed1992

A system for studying the microstructure of ingestive behavior in mice.

A system for long-term monitoring of mouse eating and drinking behavior with 6-s resolution is described. The apparatus utilizes infrared beams to monitor activity at a single feeding port and electronic contact detector circuitry to record individual licks at two drinking ports. Eight SWR/J mice were monitored using this system and data from the last day of testing with food and water were analyzed. Mice ate an average of 4.54 +/- 0.40 g of powdered food and drank an average of 5.81 +/- 0.65 ml of water. Mice had an average of 36.25 +/- 3.96 food bouts and 32.25 +/- 7.56 water bouts lasting 3.00 +/- 0.48 and 0.88 +/- 0.35 min, respectively. Information regarding the temporal association between eating and drinking and the circadian patterns of ingestion was provided, utilizing customized software that augments the system. Important implications for the use of mice in ingestion pattern research are discussed.

Animals↗
PubMed1992

Image contrast in high-resolution electron microscopy of biological macromolecules: TMV in ice.

It is shown that the contrast in high-resolution electron micrographs of biological macromolecules, illustrated by a study of TMV in ice, falls considerably below the level which should theoretically be attained. The factors which contribute to the low contrast include radiation damage, inelastic scattering, specimen movement and charging. Future progress depends on improved understanding of their contributions and relative importance. Contrast is defined as the amplitude of a particular Fourier component extracted from an image in comparison to that expected by extrapolation from separate electron or X-ray diffraction measurements. The fall in contrast gets worse with increased resolution and is particularly serious at 10 A and beyond for specimens embedded in vitreous ice, a method of specimen preparation which is otherwise particularly desirable because of the expectation that the embedded molecules should be well preserved in a near-native environment. This low contrast at high resolution is the principal limitation to atomic-resolution structure determination by electron microscopy. In spite of good progress in the direction of better images, it remains a major problem which prevents electron microscopy from becoming a simple and rapid method for biological atomic structure determination.

Bacteriorhodopsins↗
PubMed1992

Preliminary examination of the comorbidity of anxiety and depression in Parkinson's disease.

Significant anxiety in combination with depression may represent a specific depressive subtype in Parkinson's disease (PD). To ascertain the prevalence of this symptom complex, we administered a self-report survey and standardized psychological tests that measure anxiety and depression to 164 PD patients and 150 age-matched healthy spouse control subjects. The reporting of depression in combination with panic/anxiety best differentiated the two populations (38% vs. 8%). Depression and anxiety were highly correlated in relationship to clinical features of PD. Our findings suggest that clinically significant levels of depression and anxiety may frequently coexist in PD. The specific neuropathology of PD may predispose to this pattern of behavioral disturbance.

Aged↗
PubMed1992

Lifetime sexual behaviors among predominantly minority male runaways and gay/bisexual adolescents in New York City.

Lifetime sexual behaviors were examined among two samples of predominantly minority, male adolescents in New York City aged 12 to 18 (M = 16.3), believed to be at high risk for HIV infection: 59 runaway males in two residential shelters and 60 males attending a community agency (HMI) for gay and bisexual youths. Interviews regarding psychosexual milestones indicated that 93% of these youths had engaged in oral, anal or vaginal intercourse and/or anilingus, with a median of 11.0 female partners among runaway males and a median of 7.0 male partners among HMI males. Both groups initiated sexual activity at a relatively early mean age of 12.6 years. Each group reported a unique developmental sequence of psychosexual milestones. Consistent condom use was reported by 13% of the youths. One quarter of the youths reported involvement in prostitution. These findings detail the need for AIDS prevention programs for these youths.

Adolescent↗
PubMed1992

An atomic model for the structure of bacteriorhodopsin, a seven-helix membrane protein.

A three-dimensional map of bacteriorhodopsin has been obtained, at near-atomic resolution, by collecting and analysing electron diffraction patterns and electron micrographs from crystals of bacteriorhodopsin preserved at very low temperatures. The map shows a resolution of 3.5 degrees in a direction parallel to the plane of the membrane, but poorer resolution perpendicular. It shows many features well resolved from the main density of the seven alpha-helices, which we interpret as the bulky sidechains of tyrosine, phenylalanine and tryptophan, as well as a very dense feature, which is the beta-ionone ring of the retinal chromophore. Using these bulky side chains as starting points and taking account of bulges of density for the smaller side chains such as leucine, we built an atomic model for the residues between 8 and 225. There are 21 amino acids from all 7 helices surrounding the retinal and 26 amino acids contributed by 5 helices that form the proton channel. Ten of the amino acids in the middle of the proton channel are also part of the retinal-binding site. The model provides a useful basis for considering the mechanism of proton pumping and in the interpretation of other experimental data. In particular, the model suggests that the pK changes in the Schiff base must act as the means by which light energy is converted to proton pumping through the channel. Asp-96 is on the pathway from the cytoplasm to the Schiff base and asp-85 on the pathway from the Schiff base to the extracellular surface. The experimental map and the building of the model of the structure will be described, as well as our interpretation of the structural basis of the mechanism.

Amino Acids↗
PubMed1991

Donor-recipient age difference--an independent risk factor in cyclosporin-treated renal transplant recipients.

Whilst HLA matching is routine in renal transplantation the possible benefits of matching donor to recipient age have not been previously explored. The simultaneous effect on graft survival of donor and recipient age was therefore investigated for 274 consecutive first cadaver transplant recipients treated by cyclosporin immunosuppression in two centres. The overall graft survival was 77%, and was not significantly different between the two centres. Individually there was no significant effect of donor or recipient age but taken together, the difference in age significantly affected graft survival (P less than 0.01) regardless of the mode of failure. The 1-year graft survival for all failures was 66.2% when the donor was 5 or more years older. 84.5% when the donor was 5 or more years younger and 71.7% when the donor was within 5 years of the recipient's age. Multivariate analysis, taking into account other variables (HLA matching, dialysis time and type, donor/recipient sex, local/imported kidneys, sensitivity, operation time, total ischaemic time, pre-operative transfusions) indicated that age difference was the single most important variable (P less than 0.01). The only other important covariate risk factor in improving graft survival was HLA-DR matching (P less than 0.05). Donor-recipient age difference is a potentially important recipient selection criterion in cyclosporin-treated renal transplant patients.

Adolescent↗
PubMed1991

Daunomycin treatment prevents clinical expression of experimental autoimmune myasthenia gravis.

Myasthenia gravis (MG) is an autoimmune neuromuscular disease, characterized by muscle weakness and electrophysiological abnormality. No treatment which would reliably induce permanent clinical remission of MG is yet available. The therapeutic efficacy and toxic effect of daunomycin (Dm), an antibiotic of the rhodomycin group, was evaluated in murine experimental autoimmune MG. Low dosage Dm treatment effectively prevented the development of muscle weakness and its associated electrophysiological abnormality, without inducing detectable toxicity and global immunosuppression.

Animals↗
PubMed1991

A side-entry cold holder for cryo-electron microscopy.

A side-entry cold holder for cryo-electron microscopy has been constructed which can be used with no loss of image resolution or contrast at 3.4 A resolution compared to the normal room-temperature holder. A description is presented of some of the ideas and tests which we have developed during its construction and are included in the design, together with a briefer outline of the remaining limitations.

Cryopreservation↗
PubMed1991

An electronic image drift compensator for electron microscopy.

Image drift frequently occurs when temperature-controlled specimen holders are used or when there is a malfunction of the electron microscope. A simple circuit is presented which supplies a noise-free linear ramp of increasing or decreasing current suitable for manual drift compensation. It has been tested extensively with several side-entry cold stages in a Philips EM420 electron microscope equipped with a low-dose kit. The compensator does not interfere with the use of the low-dose kit and requires no modifications to the microscope.

Electric Conductivity↗