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Biomedical subjects

J N Weiss

Publications and source records attributed to J N Weiss.

126 records · Page 7Linked to original sources
PubMed1984

In vivo observation of lens protein diffusivity in normal and X-irradiated rabbit lenses.

Using the techniques of quasielastic light scattering spectroscopy we have studied in vivo the effect of X-irradiation on the diffusivity of lens proteins as a function of position in the lens and time after irradiation. The findings were compared with those for normal lenses in vivo. The experimentally observed correlation functions show marked changes in the protein diffusivity well before substantial biochemical changes take place.

Animals↗
PubMed1984

Is there a threshold level of fetal hemoglobin that ameliorates morbidity in sickle cell anemia?

When the clinical manifestations of 272 patients with sickle cell anemia are compared with their level of fetal hemoglobin (HbF), the results suggest that there may be a threshold above which HbF is effective in ameliorating the morbidity of this disease. The age of entry of these SS patients into the study ranged from birth to 56 yr; the average length of follow-up was 11 yr for a total of 3,011 patient-years of clinic observation. HbF was determined quantitatively by microchromatographic procedures; the mean for HbF was 10% +/- 6% with a range from 2% to 32%. For major organ failure, analyzed as termination events of morbidity, such as stroke or aseptic necrosis, the threshold appears to be 10%, whereas for recurrent clinical events, such as crisis or pulmonary disorders, it is 20%. No linear trend was found between HbF levels and morbidity. If a threshold exists, it is important to recognize this fact when attempts are made to raise the level of HbF in patients with sickle cell disease.

Adolescent↗
PubMed1984

Recent trends in the management of life-threatening ventricular arrhythmias.

An edited summary of an Interdepartmental Conference arranged by the Department of Medicine, UCLA School of Medicine, Los Angeles. William M. Pardridge, MD, Associate Professor of Medicine, is Director of Conferences. This study was supported in part by grants from the Public Health Service; the National Institutes of Health (HL-23970, 1978-1981); the Medical Research Service of the Veterans Administration, and the American Heart Association, the Greater Los Angeles Affiliate.

Anti-Arrhythmia Agents↗
PubMed1984

Laser light scattering spectroscopy of in vivo human lenses.

Laser light scattering spectroscopy measures the thermal random movement of protein as characterized by the diffusion coefficient. This technique has been used in assessing cataract formation in animals. The changes detected appear to predict the later development of lens opacities. The sensitivity and quantitative aspects of this technique offer advantages over other presently available methods of detecting cataract formation. First studies in humans indicated a significant correlation between the diffusion coefficient and age (P less than 0.05). The age adjusted mean diffusion coefficient for nondiabetics (4.60 +/- 0.29; mean +/- SEM) was significantly higher compared to diabetics without retinopathy (3.59 +/- 0.41; P = 0.0473), diabetics with background or preproliferative retinopathy (2.73 +/- 0.27; P = 0.0001), or to diabetics with preproliferative or proliferative retinopathy receiving laser photocoagulation within 1 year of measurement (3.02 +/- 0.37; P = 0.0012). Diabetics with laser treatment more than 1 year prior to measurement (3.96 +/- 0.51) did not differ significantly from nondiabetics.

Adolescent↗
PubMed1982

Detection of Pseudomonas aeruginosa eye infections by ultraviolet light.

Pseudomonas aeruginosa elaborates several pigment fractions that fluoresce in ultraviolet light. This fact has been used by surgeons in burn units so that treatment of subclinical P aeruginosa infections may be initiated promptly. We have determined the minimum in vitro concentration of two strains of this organism that exhibit ultraviolet light fluorescence and have applied this principle to the early detection of P aeruginosa eye infections.

Animals↗
PubMed1982

Vitreous variation in vitreous fluorophotometry.

Clinical vitreous fluorophotometry is a technique used to evaluate the early breakdown of the blood-retina barrier, which is often seen in diabetic retinopathy. However, the test does not take into account the possibility of individual variations of fluorescein diffusion in the vitreous body. This study undertook to follow the diffusion of a fluorescein solution in 20 different bovine vitreous bodies in a laboratory setting. The results showed a broad distribution of fluorescein diffusion in the sampled population. By statistical analysis, at least three subgroups, differing with respect to the fluorescein dye diffusion pattern, were identified. Further experiments suggest that variation in hyaluronic acid structure in vitreous bodies might account for these differences.

Animals↗
PubMed1981

A system for slit-lamp polaroid photography.

A system is described in which a SX-70, Alpha Model II, Polaroid, single lens reflex camera, and photoflash unit can be quickly and sturdily mounted to a slit lamp. Such a system can take sharp anterior segment prints of the eye at all slit-lamp magnifications, with white light and in the flourescein mode. The heart of the unit is the modification of an assembly initially designed to attach the camera to a light microscope. The small flash unit and power supply were designed specifically for slit lamp usage. Examples of "instant" photos of the anterior segment at different magnifications are presented.

Contact Lenses↗
PubMed1981

The effect of corneal stretch on the endothelium.

A model has been developed to describe the phenomenon of corneal stretch. In the model situation, suction is applied to the corneal surface of the bovine eye. The newly induced corneal shape forces the endothelial layer to stretch and sometimes to tear apart in places. This same type of stretch can be induced when a soft lens is placed on the bovine cornea. We postulate that drying of the soft lens produces a local flow of water from the cornea at the lens periphery with a secondary bowing of the central cornea. These results are confirmed by a decrease in the peripheral keratometry readings with an increase in the central keratometry measurements. The resultant deformation increases the posterior surface area of the cornea thus stretching the endothelium. These reversible/irreversible changes are time/drying dependent. The endothelial effects of corneal bending, as in cataract extraction, radial keratotomy and tight suture placement were investigated. As expected, when these techniques stretch the cornea, the result is endothelial changes.

Animals↗
PubMed1980

Keratopathy after oral administration of tilorone hydrochloride.

Two patients given tilorone HCl orally for varying periods of time had clinical and histopathologic ocular changes. Retrospective study of 14 cancer patients who were taking tilorone HCl orally revealed that three patients had similar ophthalmic findings accompanied by the appearance of blue halos around pinpoint light sources. Examination revealed a diffuse clouding of the epithelium sometimes associated with subepithelial infiltrates. Abnormalities seen histologically included cloudy swelling of the epithelium and cytoplasmic inclusions. By electron microscopy these were found to be myelinoid bodies. Gas chromatography and mass spectrophotometry showed that tilorone HCl was present in the cornea and conjuctiva. Visual acuity was not affected and these changes were slowly reversible with the cessation of therapy. Biomicroscopic and conjunctival cytologic examination may serve to indicate the drug's storage and potential damage in the body.

Adult↗
PubMed1980

Retinopathy after tilorone hydrochloride.

Two patients, a 34-year-old woman and a 50-year-old woman, received tilorone HCl, an experimental antitumor drug. After taking the drug orally (total dose, 152 g), the first patient developed corneal subepithelial infiltrates and toxic retinopathy characterized by fine pigment mottling of the peripheral fundus and macula with mild arteriolar narrowing. Although visual acuity was 6/6 (20/20) throughout treatment, Goldmann perimetry showed marked peripheral constriction of the visual fields and results of an electroretinogram and an electro-oculogram were abnormal. After taking the drug orally (total dose, 189 g), the second patient developed corneal subepithelial infiltrates, severe bilateral arteriolar narrowing, and mild pigment mottling of the macula. ERG and EOG were moderately attenuated. Visual fields by Goldman perimetry were within normal limits. Tilorone HCl, like chloroquine, may be an antioxidant that affects the free radical scavenging mechanism of the retinal pigment epithelium. Extensive testing should be done on all patients taking tilorone HCl in order to detect the initial manifestations of retinopathy.

Adult↗
PubMed1980

Quality of semen obtained from 627 fertile men.

Six hundred and twenty seven men, whose wives conceived within 6 month of their semen analysis, were included in this study. Attention was focused on 516 men where conception occured within 3 months of semen analysis. The quality of the seminal plasma (volume pH, fructose and calcium concentrations) and the spermatozoal characterization (concentration, motility, vitality and morphology) are given in details. It was concluded that spermatozoal motility and morpholoy are the most crucial factors in determining its fertilizing capacity. Measurement of vitality is important only in hypokinetic specimens. Sperm density is a limiting factor only below 10 million/ml. A widely scattered range of sperm concentration was found among the fathered men which may indicate that the incidence of pregnancy is a multifactorial statistical probability which increases when the quality of the semen is high.

Adult↗
PubMed1980

Relation between semen quality and fate of pregnancy: retrospective study on 534 pregnancies.

Full semen analysis including sperm and seminal plasma (SP) was performed on 534 men, within 3 months of their wives conception, 65% of the pregnant wives eventually delivered, while the remainder aborted. The abortions were divided into five groups: early abortion (6%), late abortion (3%), repeated abortion (14%), and habitual abortion (12%). SP quality of the husbands of the various groups were identical. The motility and vitality of spermatozoa of the various groups were in the same range. Sperm concentration was significantly higher in the repeated and habitual abortion groups with a tendency to polyzoospermia. The morphology of spermatozoa was much better in these two groups. Generally, sperm quality of the men whose wives were repeated or habitual aborters was better than in the other groups. We could not find any evidence in the routine semen analysis indicating that sperm quality was responsible for the abortions. The reason for the abortions seems to be a female factor or chromosomal aberrations.

Abortion, Habitual↗
PubMed1980

Lack of influence of fetal hemoglobin levels or erythrocyte indices on the severity of sickle cell anemia.

Persons with sickle cell anemia who have elevated fetal hemoglobin or lowered erythrocyte mean corpuscular volume are reputed to have less severe clinical manifestations and a greater probability of survival. This study examines the relationship between seven clinical indicators of morbidity in sickle cell anemia and seven hematological parameters that were collected from 214 patients. Risks of sickle cell crisis, acute chest syndrome, hospital admissions, cerebrovascular accident, aseptic necrosis, meningitis/septicemia, and death were used as indicators of morbidity. The hematological parameters included percent fetal hemoglobin, absolute fetal hemoglobin, percent hemoglobin A2, hemoglobin concentration, packed cell volume, mean corpuscular volume, and mean corpuscular hemoglobin concentration. Statistical analyses of the data showed no relationship between the hematological parameters and six of the seven clinical indicators of the severity of sickle cell anemia. The only significant finding was an increased risk of stroke in those patients with lower levels of fetal hemoglobin. Therefore, with this exception, there is no predictable relationship between morbidity and mortality in sickle cell anemia and levels of fetal hemoglobin or erythrocyte indices. Thus, the general belief that there is an association between severity of sickle cell anemia and the levels of fetal hemoglobin has not been established.

Adolescent↗
PubMedDate not supplied

Amitriptyline and chronic low-back pain. A randomized double-blind crossover study.

The effect of antidepressant medication on chronic low-back pain patients was studied in a randomized blind crossover study. Among those patients who completed the study, there was a 46% decrease in the use of analgesics while on amitriptyline when compared to placebo (P less than 0.005). There was also improvement in affect, but no measurable change in activity level. The MMPI profile of those patients who were unable to comply with the study protocol differed from that of patients who completed the study. The noncompliers demonstrated an elevation of the F, Pd, Pt (P less than 0.05) and Mf (P less than 0.01) scales. Although the interpretation of such a profile is left open to speculation, it may serve as an indicator of noncompliant individuals.

Activities of Daily Living↗
PubMedDate not supplied

Retinal surgery for treatment of central retinal vein occlusion.

Vitreous surgery with retinal vein cannulation and injection of tissue plasminogen activator was performed in 8 eyes of 8 patients with longstanding visual loss secondary to central retinal vein occlusion. A modest improvement in visual acuity was demonstrated in 4 of the 8 eyes, and 3 of the 8 eyes maintained the preoperative vision. Retinal vein cannulation may offer a new treatment option for patients with central retinal vein occlusion.

Aged↗