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Biomedical subjects

J Ahrens

Publications and source records attributed to J Ahrens.

At least 37 records · Page 2Linked to original sources
PubMed1997

The relationship of suture anchor failure and bone density to proximal humerus location: a cadaveric study.

The purpose of this study was to evaluate spatial variations in the pullout strength of a suture anchor in the proximal humerus, and to correlate any differences with the local mineral density (BMD). Screw-type suture anchors threaded with wire sutures were inserted at six different anchor insertion sites in 11 human cadaveric humeri (average age, 80 years). Load to failure tests with forces applied in line with the axis of insertion were performed, and bone mineral density measurements were then made at these sites. The greater tuberosity showed anterior and posterior differences in anchor pullout force (P = .03), with the posterior portion showing higher strength (154 N) than the anterior area (96 N). Neither the lesser tuberosity (185 N anterior area and 177 N posterior area) nor the humeral neck (170 N anterior and 174 N posterior area) showed significant differences, and they were statistically equivalent to the greater tuberosity. There was no demonstrable difference in BMD at any of the six sites tested. There is no support for the hypothesis that significant differences in load to failure exist among the lesser tuberosity, humeral neck, and greater tuberosity. Also, there is no support for the hypothesis that the load to failure variations for the proximal humerus are dependent on BMD. Bone mineral density appears to have no correlation with the pullout strength of a screw-type suture anchor.

Aged↗
PubMed1997

The learning curve and the health care industry.

This article will examine the learning curve and its potential impact on the health care industry. Although the learning curve has traditionally been applied to the manufacturing industry, a labor-intensive industry like health care is a prime candidate for the benefits of the learning curve. Specifically, we will look at past research on the learning curve and discuss what effects learning might have on health care costs and outcomes in the current health care environment.

Accounting↗
PubMed1991

Sexual headaches: case report, review, and treatment with calcium blocker.

A case is reported in which a patient with sexual and orgasmic headaches was treated successfully with a calcium channel blocker, diltiazem. To the best of our knowledge, this is the first case of successful treatment of sexual headaches with calcium channel blockers reported in the English medical literature. The literature on sexually related headaches is reviewed, and classification, evaluation, differential diagnosis, pathophysiology, differential diagnosis, and treatment of sexual headaches are discussed.

Adult↗
PubMed1989

Efficacy of SCH39304 in murine cryptococcosis.

Cryptococcal meningitis is increasing in frequency, in large part because of the advent of acquired immune deficiency syndrome. Using the murine cryptococcosis model, a new oral triazole, SCH39304, has been compared with two drugs in clinical use, fluconazole and amphotericin B. BALB/c mice (nu/nu and nu/+) were challenged intracerebrally or intranasally. Oral treatment was given daily with SCH39304 at doses of 1 to 60 mg/kg of body weight or fluconazole at doses of 1 or 5 mg/kg of body weight. Amphotericin B was given intraperitoneally three times weekly, at doses of 3 or 6 mg/kg. After intracerebral challenge, SCH39304 prolonged survival in doses as low as 1 mg/kg, a dose at which fluconazole was ineffective. At equal doses, SCH39304 consistently increased survival more than did fluconazole but not longer than did amphotericin B. SCH39304 significantly lowered colony counts in brains more than did fluconazole but no more than did amphotericin B. SCH39304 was also superior to fluconazole after intranasal challenge at equal doses. SCH39304 appears to be superior to fluconazole in mice when the drugs are given at equal doses. Clinical trials are warranted.

Amphotericin B↗
PubMed1989

Experimental murine chromomycosis mimicking chronic progressive human disease.

Congenitally athymic (nu/nu) mice, mice defective in NK cell and macrophage function (bg/bg), and normal BALB/c mice were inoculated sc with 10 conidia of Fonsecaea pedrosoi (FP). In immunologically intact and immunodeficient mice, a local infection developed approximately 2 weeks post-inoculation and enlarged over 1-2 weeks. In bg/bg and normal nu/+ mice, lesions resolved within 5-6 weeks. However, nu/nu mice continued to have enlarging sc lesions during greater than 4-6 months of observation. These eventually metastasized. Lesions contained few hyphal elements and massive numbers of sclerotic bodies. Five weeks after inoculation, 10 conidia forming units/gm of tissue were recovered from lesions. Delayed type hypersensitivity and serum antibody to FP antigens were demonstrated. Adoptive transfer of lymphocytes from nu/+ mice was followed in 2 months by the resolution of the lesions.

Animals↗
PubMed1988

In situ localization of antigens of Histoplasma capsulatum using colloidal gold immune electron microscopy.

Histoplasma capsulatum contains multiple antigens, among them the H antigen and M antigen, which are useful in serologic testing for histoplasmosis. We prepared 7 mouse monoclonal antibodies (5 IgG, 2 IgM) to histoplasmin, and compared these with polyclonal histoplasmin antibodies raised in rabbits and mice. Both monoclonal and polyclonal antibodies were high titered by ELISA. Colloidal gold immune electron microscopy (CGIEM) showed that polyclonal antibodies to histoplasmin or H antigen bound at multiple sites in the cell wall, cytoplasm, and nucleus of Histoplasma yeast cells. In contrast, antibodies to M antigen selectively label the cell membrane and antibodies to alkali soluble cell wall antigen label only the cell wall. Polyclonal antibodies cross reacted extensively with other fungi, both by ELISA and CGIEM. Monoclonal antibodies stained only cytoplasmic epitopes, but also cross reacted with other fungi by electron microscopy. Only periodate treated H antigen elicited polyclonal antibodies which were more specific than those of untreated H antigen or histoplasmin.

Animals↗
PubMed1988

Experimental pulmonary histoplasmosis and emphysema.

Chronic pulmonary histoplasmosis often occurs in the setting of emphysema. However, it is unknown whether emphysema directly predisposes to the development of the necrotizing lesions of chronic pulmonary histoplasmosis. We evaluated this possibility using a murine model of pulmonary histoplasmosis. Using intratracheal inoculation of elastase, we induced pulmonary emphysema in Balb/c mice. When mice with emphysema were challenged intranasally with H. capsulatum (HC) yeast cells, the course of their disease was not significantly different from that of normal mice. Mice were also exposed to HC antigens by sublethal intranasal challenge with viable or heat-killed HC, or immunized with histoplasmin. Prior sublethal challenge with viable HC did not cause prolonged illness or increased mortality in the setting of emphysema. In contrast, such mice were protected against a severe rechallenge. Additional studies showed that intranasal administration of heat-killed HC or subcutaneous immunization with histoplasmal antigens had neither protective nor deleterious effects on the course of histoplasmosis. Therefore, in this murine model, we could not substantiate an interaction of underlying emphysema with acute primary or rechallenge pulmonary histoplasmosis.

Animals↗
PubMed1987

Experimental histoplasmosis in the beige mouse.

Mice carrying the beige mutation (bg/bg) on a C57Bl/6 background were challenged with Histoplasma capsulatum. bg/bg mice had higher mortality and higher lung tissue fungal counts in their lungs than either bg/+ or C57Bl/6 mice challenged with equal inocula. Immunologic studies showed that bg/bg mice developed normal delayed-type hypersensitivity (DTH) reactions to histoplasmin, but had deficient NK cell cytotoxic activity against YAC-1 target cells. Studies of macrophage killing of H. capsulatum in vitro showed that T lymphocytes of either bg/+ or bg/bg mice were able to activate fungal killing by bg/+ but not by bg/bg macrophages. These studies, while not excluding a role for the NK cell, suggest that macrophage dysfunction may be critical in the greater susceptibility of the bg/bg mouse and, by extension, that macrophage function is of major importance in host defense against H. capsulatum.

Animals↗
PubMed1986

Treatment of murine coccidioidal meningitis with fluconazole (UK 49,858).

Male ICR mice were challenged intracerebrally with endospores of Coccidioides immitis and then treated with water (control), fluconazole, amphotericin B (Fungizone), or ketoconazole (Nizoral). All three drugs markedly prolonged survival, and all three drugs lowered brain colony counts of C. immitis. Survival of mice treated orally with fluconazole at the high dose was longer than in the ketoconazole treated group. Amphotericin B was more efficacious than fluconazole. Further investigations are needed to determine the efficacy of fluconazole in treatment of coccidioidal meningitis.

Amphotericin B↗
PubMed1986

Treatment of murine histoplasmosis with UK 49,858 (fluconazole).

Fluconazole was compared with ketoconazole and with amphotericin B in treatment of pulmonary histoplasmosis in immunologically intact mice and in congenitally athymic nude mice. Both fluconazole and amphotericin B increased survival and reduced fungal burden in normal mice. All 3 drugs equally prolonged survival of nude mice challenged with Histoplasma capsulatum, and all effectively reduced the fungal burden. Fluconazole may be a useful antifungal drug in treatment of murine histoplasmosis.

Animals↗
PubMed1985

Itraconazole treatment of murine aspergillosis.

ICR mice were challenged with conidia of Aspergillus fumigatus given either intranasally or intravenously, and treated beginning 1 day later with itraconazole, amphotericin B, or the vehicles for these two agents. Mice challenged intravenously and treated with either antifungal drug had prolonged survival over controls, and had lower tissue counts in the kidneys than the controls. However, mice challenged intranasally had neither prolonged survival nor lower lung tissue counts than the controls.

Amphotericin B↗
PubMed1985

Detection of histoplasmal antigens in mice undergoing experimental pulmonary histoplasmosis.

A micro-ELISA assay was developed for the quantitation of Histoplasma capsulatum antigen in lungs, bronchoalveolar lavage fluid (BALF), and serum of intranasally infected mice. As little as 0.2 ng of antigen/ml could be detected. During the course of experimental histoplasmosis, immunologically intact, thymus-containing mice (nu/+) had detectable histoplasmal antigens in their lungs, serum, and BALF within 1 day of challenge. Lung, BALF, and serum antigen concentration rose to a peak 2 wk after challenge; in nu/+ mice, antigen concentration then declined through the next 2 wk. In contrast, athymic nude mice have depressed cell-mediated immunity; their antigen concentration continued to rise throughout the course of progressive, ultimately lethal, illness. Antigen concentrations correlated with quantitative cultures of the lungs and BALF. There was little cross reactivity in mice challenged intranasally with Candida albicans or Blastomyces dermatitidis. The sensitivity of this test, and the apparently minimal cross reactivity, suggest that the micro-ELISA for histoplasmal antigen might have significant clinical application in diagnosing and monitoring the course of histoplasmosis.

Animals↗
PubMed1984

[Efficacy of the immunostimulant Broncho-Vaxom].

In a 6-month placebo-controlled double-blind multicenter study in 230 patients with recurrent respiratory tract infections, the therapeutic efficacy of Broncho-Vaxom was demonstrated by comparing infection incidence and severity as well as antibacterial medication. Investigators and patients agreed that Broncho-Vaxom exerts a significantly greater protective effect than placebo. Reports of side effects were more frequent with placebo as compared to Broncho-Vaxom.

Adjuvants, Immunologic↗