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Biomedical subjects

J H Theis

Publications and source records attributed to J H Theis.

At least 19 recordsLinked to original sources
PubMed1994

Detection by immunoblot assay of antibodies to Taenia solium cysticerci in sera from residents of rural communities and from epileptic patients in Bali, Indonesia.

Several studies from Bali have indicated the presence of Taenia solium. Relatively little has been reported, however, implicating human exposure to this parasite on Bali based upon the prevalence of anti-T. solium antibodies in asymptomatic and epileptic individuals. This study was conducted to determine by immunoblot assay and ELISA the frequency of anti-cysticercus antibodies in two groups of Balinese. Among 746 residents of four ecologic zones, 94 (13%) were positive by immunoblot. Of 74 epileptic patients from throughout the island, 10 (14%) were positive by immunoblot and 8 (11%) by ELISA; however, only 4 (22%) of the 18 sera positive in either test were positive in both assays. The previously defined high specificity and sensitivity of immunoblot indicates that T. solium cysticercosis is well established in Bali and that a significant amount of epilepsy may be due to neurocysticercosis.

Adolescent↗
PubMed1992

Humoral responses following immunization with Leishmania infantum (ex. Oklahoma): a comparison of adjuvant efficacy in the antibody responses of Balb-C mice.

Adjuvants are commonly used in immunization protocols for the purpose of augmenting immune responses to antigens. The antigenic profile of Leishmania infantum (ex. Oklahoma) is described and the efficacies of three adjuvants delivered coincidentally with killed promastigotes are compared, by measuring relative serologic responses of Balb-C mice to specific antigenic determinants. Western blotting techniques were employed to visualize humoral responses to isolated antigens; serologic profiles were compared and contrasted. Four immunization protocols utilizing Freund's complete adjuvant, glucan adjuvant, lipovant adjuvant or phosphate-buffered saline, in conjunction with killed L. infantum (ex. Oklahoma) promastigotes were executed in parallel. All groups receiving adjuvant protocols developed enhanced serologic responsiveness. Similar profiles were observed in mice treated with glucan or lipovant. Animals receiving promastigotes in Freund's complete adjuvant also developed strong humoral responses, binding cross-reactive epitopes not recognized by other groups. Our findings indicate that glucan and lipovant present effective adjuvant alternatives, to Freund's complete adjuvant and may be of value in immunization against visceral leishmaniasis.

Adjuvants, Immunologic↗
PubMed1992

Seasonal prevalence of Taenia taeniaeformis: relationship to age, sex, reproduction and abundance of an intermediate host (Peromyscus maniculatus).

Livers from 4,501 deer mice (Peromyscus maniculatus) collected from a weedy habitat in northeastern California during 48 consecutive monthly samplings were examined microscopically for Taenia taeniaeformis larva. Although there were pronounced seasonal fluctuations in host density, there were no significant annual or season-related differences in cestode intensities in adult deer mice. There were no significant differences in prevalences associated with sex of the host, nor were there significant changes in level of reproduction noted between infected and non-infected hosts. There were, however, significant differences in prevalences between young (1.2%) and adult (4.2%) hosts. Plausible mechanisms for this age-related difference in prevalence rates include (1) differential susceptibility due to the activity pattern of adult mice and/or (2) passive immunity in neonates as a result of colostrum- and/or transplacentally-transferred immunoglobulins and (3) capture of subadult animals before they had completed the period of highest susceptibility to T. taeniaeformis. Density of larvae per mouse liver was determined during a 21 mo consecutive period. The intensity of T. taeniaeformis larvae was not significantly different between the sexes of the adult mice. The larval stage showed an overdispersion pattern within the adult population. These results suggest that determinations of T. taeniaeformis abundances can be accurately made, at least in this P. maniculatus population, at any time of the year provided adjustment is made for the relative age structure of the host population.

Age Factors↗
PubMed1990

Change in the isoenzyme composition of acid phosphatase in murine peritoneal macrophages exposed to or infected with Trypanosoma cruzi.

The effect of infection with Trypanosoma cruzi on the activity and isoenzyme composition of acid phosphatase within individual murine peritoneal macrophages maintained in vitro was studied. Concentrations of acid phosphatase activity and number of intracellular parasites were quantitated by using a computer-assisted cytospectrophotometry system. Changes in the isoenzyme composition of macrophages during infection with T. cruzi were detected by comparing the patterns of acid phosphatase levels between macrophages treated in the absence and presence of an enzyme inhibitor. It was observed that the concentration levels of acid phosphatase activity in macrophages did not change significantly by infection with T. cruzi. Also, the concentration levels of acid phosphatase activity did not change in macrophages uninfected but exposed to T. cruzi. On the other hand, the isoenzyme composition of acid phosphatase did change in macrophages exposed to or infected with T. cruzi. These results demonstrate that Trypanosoma cruzi affects the acid phosphatase composition of macrophages.

Acid Phosphatase↗
PubMed1989

Decrease of acid phosphatase activity in murine peritoneal macrophages infected with Leishmania donovani.

The effect of infection with Leishmania donovani on the activity and isoenzyme composition of acid phosphatase within individual murine peritoneal macrophages maintained in vitro was studied. Concentrations of acid phosphatase activity and number of intracellular parasites were quantitated using a computer-assisted cytospectrophotometry system. Changes in the isoenzyme composition of macrophages during infection with L. donovani were detected by comparing the patterns of acid phosphatase levels between macrophages treated in the absence and presence of an enzyme inhibitor. It was observed that the concentration levels of acid phosphatase activity in macrophages were decreased significantly by infection with L. donovani. An inverse relation existed between concentration of acid phosphatase activity and the number of intracellular L. donovani. Reduced concentrations of acid phosphatase activity were also observed in macrophages uninfected but exposed to L. donovani. The isoenzyme composition in macrophages did not change during the course of infection with L. donovani. These results demonstrate that L. donovani reduces the acid phosphatase activity of macrophages.

Acid Phosphatase↗
PubMed1989

Annual cyclicity of gall stone prevalence in deer mice (Peromyscus maniculatus gambelii).

The prevalence of gall stones (100% cholesterol) in a deer mouse (Peromyscus maniculatus) population located in Siskiyou County, California (USA) was studied on a monthly basis from February 1985 through January 1988. During each year we documented a pronounced annual cyclicity with peak prevalence (31 to 53%) during the winter and low prevalence (2 to 3%) during late summer. Gall stone prevalence was not related to sex or age of the animal. The earliest onset of gall stone production and the maximum prevalence achieved were associated with the greatest abundance of deer mice; lower levels of population abundance were associated with later onset of gall stone production and lower peak prevalences. This association of gall stone prevalence with both season and population abundance levels suggests that the causative factor(s) is/are related to the quality and availability of the diet.

Age Factors↗
PubMed1988

Hazards of angioscopic examination: documentation of damage to the arterial intima.

The fiberoptic scope is increasingly used in the coronary and peripheral arteries to quantitate the degree and type of arterial obstructive disease and to inspect the results of procedures such as bypass grafting and laser irradiation of obstructive lesions. Since little is known about this instrument's potential complications, we passed a variety of fiberoptic scopes (1.8 to 3.6 mm outer diameter) in fresh postmortem pig coronary arteries and live monkey and canine peripheral arteries, and observed the intraluminal anatomy through the angioscope. No perforations were created, but ridges rising from the vascular luminal surface, avulsion of the endothelial lining, and small flaps attached at one end to the vessel wall were observed. Histologically, subintimal and medial tears were evident. Inserting large diameter scopes or making frequent passes (10 to 100) in coronary arteries increased intravascular injury. The use of small diameter flexible scopes or infrequent passes (less than 10) in the larger iliac and femoral arteries of live monkeys and dogs resulted in a lower frequency of myointimal sloughing or flap formation. Current fiberoptic scopes are not ideal angioscopes; they have a rigid tip, cannot be steered adequately, and are relatively stiff, resulting in a high probability of intraluminal injury, especially when used in small tortuous arteries. To decrease the risk of such injury, we recommend gentle manipulations while passing the scope and use of the smallest diameter scope possible. We further suggest limited use of the fiberscope, or at least limiting the number of passes in small vessels such as coronary arteries.

Animals↗
PubMed1987

Effects of simultaneous viewing and vaporization of plaques using the steerable, laser-heated metal cap in the atherosclerotic monkey model.

A steerable, fiberoptic catheter coupled to a laser light guide tipped with a metal cap was used. Four monkeys fed an atherogenic diet for 7-8 years were angiographed and were found to have extensive mural plaque in the iliac arteries. Plaque sites in these monkeys were vaporized using the laser-heated metal cap. Energies of 1.5-9 Joules were employed. Application of the energy was tangential of perpendicular to the plaque. Lased sites were examined histologically at 24 hr or at 3 months after treatment. No effect was seen at 1.5 Joules. Three to six Joules tangentially produced a superficial lesion that extended into the tunica intima. Six Joules perpendicularly produced a burn into the tunica adventitia, with damage to the vasavasorum. Nine Joules tangentially produced a burn into the tunica media. Three months after treatment, this lased site showed no stenosis or aneurysm formation.

Animals↗
PubMed1987

Exotic stock of Trypanosoma cruzi (Schizotrypanum) capable of development in and transmission by Triatoma protracta protracta from California: public health implications.

A stock of Trypanosoma cruzi was recovered from a Triatoma dimidiata from Tegucigalpa, Honduras. This stock was shown to be capable of development and transmission by native California Triatoma protracta protracta. Isozyme analysis indicated that this T. cruzi is closely related to the Tehuantepec strain and to a lesser extent the Miles' zymodeme 1 strain. The potential public health significance of development and transmission of exotic stocks of T. cruzi by native reduviids is discussed.

Animals↗
PubMed1985

Agent of Chagas' disease from Honduran vector capable of developing in California insects: implications for cardiologists.

An exotic strain of Trypanosoma cruzi recovered from Triatoma dimidiata from Tegucigalpa, Honduras, was shown by isoenzyme studies to be closely related to the Miles' zymodeme 1 and laboratory reference strain Tehuantepec. It was injected into Swiss random-bred ICR mice. Clean Triatoma protracta nymphs and adults, which had been captured in Winters, California, fed on inoculated mice and were then examined over a 15-month period. Their feces contained multiplying epimastigote and infective trypomastigote forms of T. cruzi. This shows that exotic strains of T. cruzi can develop and survive for long periods in local California vectors. The increasing number of immigrants from Central America who enter California and other states may have public health implications in regard to the introduction of pathogenic strains that are capable of producing cardiomyopathy. Cardiologists who examine patients with cardiomyopathy from Central and South America should rule out Chagas' disease as a cause, since pathogenic T. cruzi strains are present in most Central and South American countries.

Animals↗
PubMed1984

Acute and chronic complications of laser angioplasty: vascular wall damage and formation of aneurysms in the atherosclerotic rabbit.

Acute and chronic vascular responses to laser exposure in atherosclerotic rabbits were studied. In 7 rabbits fed an atherogenic diet for 3 to 5 months before the study to induce aortic atherosclerosis, a flexible quartz fiber, 400 micron core diameter, attached to an argon ion laser was passed anterogradely or retrogradely to the atherosclerotic ascending aorta. The laser was turned on using power intensities of 1 to 2 W for 3 seconds. After laser treatment, the aortas were studied acutely in 3 rabbits and chronically in 4 rabbits after recovery for 1 to 14 days. In 2 rabbits studied acutely, the argon laser produced a vaporized crater within the atherosclerotic plaque at the endothelial surface; however, in 1 there was also vascular damage extending deep into the medial layer. In addition, aortic aneurysm with muscular wall damage occurred in 2 of the 4 animals studied chronically. Thus, vascular complications may arise when catheter laser angioplasty is randomly applied without visualizing specific plaque targets or without using safe dose increments of power intensities and durations of exposure. This study suggests caution in the clinical use of intensive phototherapy to cardiovascular lesions and stresses the need for further understanding of laser vascular consequences before application of laser angioplasty in patients.

Animals↗
PubMed1983

Effects of laser irradiation on human erythrocytes: considerations concerning clinical laser angioplasty.

Recent studies demonstrate the potential use of laser to vaporize human coronary atherosclerotic plaques. The laser energy is transmitted through flexible quartz fiber and discharged intravascularly. Since red blood cells could be exposed to intense heat, we examined effects of laser irradiation on human erythrocytes. Blood was obtained and placed in 5 ethylene diaminetetracidic acid (EDTA) vials for each normal donor. A flexible 400 microns diameter core quartz fiber coupled to an argon-ion laser source was positioned 1 cm above the surface of 1.5 ml blood. Four vials were exposed to 5 W laser beam for 5, 10, 15, or 20 s; the remaining vial was left untreated. Packed cell volume fell primarily during the first 5 s of laser exposure (p less than 0.01) and plateaued beyond 5 s. Plasma hemoglobin (Hgb) rose progressively with each increased duration of exposure (p less than 0.01). This study indicates that lysis of erythrocytes occurs in cells exposed directly to the laser beam. However, beyond the direct beam, damage to red cell membrane took place as evident by progressive Hgb leakage into plasma despite no further cell lysis. These observations require consideration during clinical laser angioplasty.

Erythrocyte Indices↗
PubMed1982

Prevalence of heartworm (Dirofilaria immitis Leidy) in coyotes from five northern California counties.

Prevalence rates of heartworm in coyotes was estimated for five northern California counties by examining hearts of coyotes obtained from federal or private trappers. Prevalence rates range from 8.3-27.3%, but the proportion of infected coyotes can vary between two regions of the same county. In general, it seems that higher infection rates are found in the foothill regions of the Coastal Range and Sierra Nevada, decreasing towards the floor of the Sacramento Valley as well as at higher elevations. The use of coyotes as sentinel animals for detecting natural foci of transmission is postulated.

Animals↗