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Biomedical subjects

S T Brown

Publications and source records attributed to S T Brown.

At least 37 records · Page 2Linked to original sources
PubMed1992

Extraneural cysticercosis presenting as a tumor in a seronegative patient.

A case of cysticercosis involving only the sternocleidomastoid muscle of an otherwise-healthy pregnant woman is presented. An enzyme-linked immunoelectrotransfer blot assay for cysticercosis was nonreactive. The clinical features of extraneural cysticercosis are reviewed with special attention to musculocutaneous involvement. The results of serological tests for such patients may not be positive and histopathology remains the only reliable method for confirming the diagnosis of cysticercosis.

Adult↗
PubMed1992

Pulmonary mycobacterial infections associated with neoplasia.

Patients with cancer are at increased risk for disease caused by mycobacteria when there is immunosuppression resulting from the underlying disease or its treatment. Pulmonary disease is usual with Mycobacterium tuberculosis or with mycobacteria other than M tuberculosis (MOTT) and atypical presentations with extrapulmonary dissemination occur frequently. No clinical features reliably distinguish between disease caused by M tuberculosis or MOTT. The incidence of M tuberculosis infection depends on a history of prior exposure in patients and on patterns of disease within hospitals and the surrounding community. Infection with different species of MOTT reflects their environmental prevalence. Diagnosis of mycobacterial infection can be clinically challenging and must be pursued aggressively. Despite recent improvements in clinical and laboratory methods, diagnosis of mycobacterial infection may take weeks. Recent increases in the incidence of M tuberculosis infection and the emergence of drug-resistant strains require heightened alertness to its diagnosis and careful epidemiological control measures to prevent continued spread of this contagion. M tuberculosis with routine antimicrobial susceptibility responds well to conventional therapy when initiated early. Prophylaxis of tuberculin positive patients is effective and should be started before immunosuppressive therapy. Guidelines for therapy of MOTT depend on the species isolated but remains poorly defined in most cases. There are several new compounds that may be useful for treatment of drug-resistant species of MOTT. New methods for the rapid diagnosis, speciation, and epidemiological investigation of mycobacterial infection are being developed, and some are available for clinical application. Nonetheless, the timely diagnosis of mycobacterial disease in patients with cancer remains a challenge of increasing clinical importance.

Antitubercular Agents↗
PubMed1991

Progressive disseminated infection with Mycobacterium avium complex after intravenous and oral challenge in cyclosporine-treated rats.

Male Sprague-Dawley rats, immunosuppressed with cyclosporine (CsA), developed disseminated infection after intravenous or oral challenge with Mycobacterium avium complex (MAC). Disseminated infection leading to bacillemia could be established after intravenous inoculation with as few as 5 x 10(3) organisms. When CsA was not given or when CsA was stopped 1 month after infection, animals cleared the bacilli from blood and tissue. Animals developed disseminated infection after oral challenge with as few as 10(6) organisms. Persistent bacillemia occurred when organisms in the spleen exceeded 10(7). Differences in virulence among strains were observed. Infected tissues showed histopathologic changes similar to those seen in patients with AIDS. The CsA-treated rat is a new model that appears useful for studies of the virulence of MAC strains and the pathogenesis of disseminated MAC infection.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Correction of microcytosis following elimination of an occult source of aluminum contamination of dialysate.

A higher prevalence of aluminum-associated microcytic anemia was noted in hemodialysis unit A (n = 67) compared to unit B (n = 39). This finding could not be explained by differences in the aluminum content of reverse osmosis (RO) water or intake of antacids containing aluminum by patients in the two units. An intermittent source of aluminum contamination was suspected when water aluminum and total dissolved solutes (TDS) were measured at several sites in the water treatment facility of unit A. A one-way valve that maintained unidirectional flow in an RO bypass circuit was found missing. Intermittent pressure changes in this circuit altered the direction of water flow causing mixing of partially purified water with RO water. Installation of the valve stopped contamination and resulted in a decrease in plasma aluminum concentration from 183 +/- 12 micrograms/L to 76 +/- 7.3 micrograms/L, erythrocyte aluminum concentration from 210 +/- 31 micrograms/L to 61 +/- 9 micrograms/L and microcytosis from 58% to 8% in patients (n = 48) when measured 6 months later. Because contamination was missed in spite of water testing at the RO site, these findings underscore the importance of measuring water aluminum and TDS content at the dialysis stations. Frequent water testing at dialysis stations, familiarity with the design of water treatment facilities, and recognition of aluminum overload can lead to early detection and correction if similar types of aluminum contamination should occur.

Aluminum↗
PubMed1989

Application of an erythrocyte aluminum assay in the diagnosis of aluminum-associated microcytic anemia in patients undergoing dialysis and response to deferoxamine therapy.

A method for measuring erythrocyte aluminum content was developed. Erythrocyte aluminum levels correlated with plasma aluminum concentrations in normal controls and in patients undergoing dialysis (r = 0.90, p less than 0.001). In vitro studies showed that erythrocyte aluminum concentrations were not altered by contamination of blood samples, which is a common problem with plasma determinations. The need for anticoagulation and rapid processing were disadvantages of this assay. In the dialysis population studied, the correlative data between mean cell volume and both plasma and erythrocyte aluminum levels (r = -0.50, p less than 0.001; and r = -0.69, p less than 0.001) and lack of correlation with serum ferritin suggested that aluminum overload and not iron deficiency was the cause of microcytic anemia. Patients undergoing continuous ambulatory peritoneal dialysis had lower plasma and erythrocyte aluminum levels and absence of microcytic anemia compared with patients undergoing hemodialysis. Therapy with deferoxamine in 13 patients with aluminum-related microcytic anemia resulted in a decrease in erythrocyte and plasma aluminum content in all patients (265.5 +/- 69.2 micrograms/L to 22.6 +/- 9.7 micrograms/L and 196 +/- 30 micrograms/L to 129 +/- 13.8 micrograms/L). The relatively smaller decrease in plasma aluminum levels suggested mobilization of aluminum from tissues other than erythrocytes. Aluminum chelation most probably occurred from premature erythrocytes, because in vitro studies showed that deferoxamine was unable to chelate aluminum from mature erythrocytes. Hemoglobin level, hematocrit measurement, and mean cell volume showed significant improvement (p less than 0.001). Ten patients showed normalized mean cell volume after 6.2 +/- 2 months of therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Aluminum↗
PubMed1988

Ethylene glycol intoxication: evaluation of kinetics and crystalluria.

Ethylene glycol and glycolate kinetics were studied in two cases of ethylene glycol intoxication with maximal ethylene glycol/glycolate concentrations of 40.9/26.8 and 56.4/22.4 mmol/liter, respectively. Both patients survived, but with prolonged renal failure, upon treatment with bicarbonate, ethanol, and hemodialysis. Glycolic acid was the major cause of the metabolic acidosis in both cases; lactate levels were only slightly elevated. Kinetic calculations showed that both ethylene glycol and glycolate were distributed in total body water with plasma half-lives of 8.4 and 7.0 hours, respectively. The half-life of ethylene glycol was increased more than 10-fold by ethanol treatment alone. Calcium oxalate monohydrate crystalluria was dominant in both cases, but in one was preceded by a short period with mainly dihydrate excretion; crystalluria was not present upon admission. Repetitive urine microscopy in search of needle- or envelope-shaped crystals should be performed when ethylene glycol intoxication is suspected.

Acidosis↗
PubMed1988

Complications from permanent hemodialysis vascular access.

From 1981 to 1986 a total of 499 operations were performed for permanent hemodialysis vascular access in 230 patients. At least 1 year's follow-up was achieved in all cases. This series is divided into 326 primary procedures and 173 secondary procedures. Of the primary procedures, there were 160 autogenous fistulas and 166 expanded polytetrafluoroethylene (PTFE) fistulas. The 156 secondary procedures consisted of 124 thrombectomies, 20 repairs of pseudoaneurysm, 12 fistula ligations, and 17 fistula excisions. The infectious complication rate (29/482) was 6%. Mean length of patency was 3.1 years for autogenous wrist fistula, 2.6 years for elbow fistula, 1.9 years for forearm loop PTFE, 2.1 years for straight forearm PTFE, 1.6 years for femoral popliteal PTFE, and 1.4 years for femoral arteriovenous loop PTFE. A vascular steal syndrome occurred in 8% of patients with autogenous elbow fistulas (4/48), compared with 1.7% (2/112) of patients with wrist fistulas and 1.8% (3/166) of those with PTFE fistulas. All infected fistulas required excision, and all fistulas associated with the steal syndrome required ligation. Use of PTFE to construct permanent hemodialysis vascular access has a significantly higher incidence of thrombosis, infection, pseudoaneurysm formation, and limb loss (p less than 0.01 for all complications) and a significantly lower mean length of patency (p less than 0.0001) when compared with autogenous fistulas. Age, sex, hypertension, diabetes mellitus, and the use of perioperative antibiotics were not found to be related significantly to access complications.

Adolescent↗
PubMed1987

Fibronectin gelatin-binding activity: effects of platelet thrombospondin, serum, and plasma.

Platelet thrombospondin and an unidentified but biologically similar plasma protein were shown to inhibit the gelatin-binding activity of fibronectin. Inhibition of fibronectin gelatin-binding activity was identified and quantitated by using latex-fibronectin particles in combination with latex-gelatin particles in a new competitive aggregation assay. Inhibition was expressed as the reciprocal of the dilution of test sample required to produce a 50% return of baseline control aggregation rate (inhibitor units). Serum and plasma from healthy donors (n = 60) showed similar reductions in fibronectin gelatin-binding activity (47.9 +/- 12.9 and 49.4 +/- 12.7 inhibitor units per milliliter, respectively). However, serum fibronectin gelatin-binding activity per milligram of fibronectin was significantly less than that of plasma. The addition of calcium chloride to platelet-rich plasma resulted in a similar reduction in fibronectin gelatin-binding activity per milligram of fibronectin. No change was observed after recalcification of platelet-poor plasma. Washed platelets (1 X 10(9)/ml) in Tris HCl buffer released 18 +/- 8 fibronectin inhibitor units per milliliter after calcium ionophore A23187 addition. When inhibitor-rich preparations from platelets and plasma were chromatographed on Sepharose CL-6B, the inhibitors eluted at the same location. Inhibitor-rich eluates from both sources bound to heparin-Sepharose and eluted with 0.45 mol/L NaCl. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of purified inhibitor preparations demonstrated a major protein band with an approximate molecular weight of 185 kd. Western blot analyses using antiplatelet thrombospondin identified the platelet-derived inhibitor as thrombospondin but failed to react with the plasma-derived inhibitor. These data demonstrated that platelet-released thrombospondin was responsible for the reduction in fibronectin gelatin-binding activity seen in serum. An unidentified plasma factor also inhibits fibronectin gelatin binding.

Adult↗
PubMed1985

Serological response to syphilis treatment. A new analysis of old data.

One important aspect of the posttreatment evaluation of patients with early syphilis is assessment of serological test results. Using information previously collected from 818 patients in the Early Syphilis Study, we evaluated the seroresponse of people treated for primary or secondary syphilis. We generated curves describing the VDRL titer declines with time. The VDRL titer declined approximately fourfold at three months and eightfold at six months. These observations will allow clinicians to identify treatment failures or reinfections at the earliest possible time during their follow-up.

Antibodies, Bacterial↗
PubMed1985

Tenckhoff catheter obstruction resulting from invasion by Curvularia lunata in the absence of peritonitis.

A 60-year-old black woman on continuous ambulatory peritoneal dialysis (CAPD) presented with Tenckhoff catheter malfunction. She exhibited no signs or symptoms of acute peritonitis. Darkly pigmented plaques were adherent to the inner wall of the catheter and exchange tubing focally throughout its length. Similar material was adherent to the protein coagulum in the dialysis bag. The Tenckhoff catheter and tubing were removed, and hemodialysis was initiated. Cultures of the catheter and the dialysate protein coagulum grew the saprophytic soil fungus, Curvularia lunata. Histologic examination of the catheter and tubing demonstrated penetration of each by hyphae. Catheter removal alone was sufficient to eradicate the fungus since recurrence of colonization or peritonitis has not occurred following the resumption of CAPD. Peritonitis produced by opportunistic pathogens especially fungi is increasingly common. Although Curvularia species have been implicated in pulmonary and cerebral mycetomas, allergic bronchoalveolar disease, and keratitis, they have not been reported previously to cause peritonitis or catheter malfunction in CAPD patients. Fungal invasion of CAPD catheters can produce mechanical obstruction even in the absence of peritonitis. Such colonization does not preclude resumption of chronic peritoneal dialysis at a later date.

Catheters, Indwelling↗
PubMed1985

Development and evaluation of a new kinetic assay for the quantitation of fibronectin gelatin-binding activity.

A new rapid and sensitive kinetic assay that measures the gelatin-binding activity of fibronectin has been developed. This assay is based on the rate of fibronectin-mediated aggregation of covalently coupled latex-gelatin particles. The addition of human plasma and serum resulted in aggregation rates proportional to the concentration of fibronectin in the test sample. This assay was inhibited by the addition of gelatin, demonstrating substrate specificity. This new assay requires 50 microliter of sample and can be performed within 5 minutes. Particle aggregation rates were affected by pH, heparin, and coupled gelatin concentration per milligram of latex. Maximum aggregation rates were observed at pH 8.0. Heparin was not an absolute requirement for particle aggregation but enhanced rates up to 1 U heparin/ml with little additive effect at greater concentrations. Heparin had a relatively greater effect on assays performed in acidic buffers. The concentration of gelatin per milligram of latex was rate limiting up to approximately 50 micrograms gelatin/mg latex with little change in aggregation rates at higher concentrations. Good correlation between total antigenic fibronectin (electroimmunoassay) and fibronectin gelatin-binding activity (latex-gelatin kinetic aggregation assay) was demonstrated in plasma from normal blood donors. This new assay will allow further definition of the relationship between fibronectin gelatin-binding activity and antigenic fibronectin in normal and pathophysiologic states.

Electrophoresis, Polyacrylamide Gel↗
PubMed1984

Sexually transmitted diseases and infertility.

In the past decade, involuntary childlessness has become a major problem in many areas of the world. At the same time evidence confirms a link between sexually transmitted diseases (STDs) and the burgeoning infertility problem. STDs can adversely affect fertility by three primary mechanisms: (1) pregnancy wastage; (2) neonatal deaths; and (3) obstruction of either male or female reproductive ducts. STD control programs have been effective in preventing sequelae of disease, including infertility. The first step in developing such a program is to identify the magnitude and distribution of the problem, and to identify the specific agents most commonly involved. Subsequently, an STD control program emphasizing the prevention of infertility, can be incorporated into the existing health care system whenever STDs are an important cause of infertility.

Chlamydia Infections↗
PubMed1984

Control of sexually transmitted diseases: view from the United States of America.

Past sexually transmitted disease (STD) control efforts in the United States of America have generally permitted a timely response to changes in intervention technology, antibiotic resistance, public funding, and media interest. Today, however, the expansion of STD organisms and syndromes at logarithmic rates has taxed our traditional labour intensive control approaches. We describe briefly the history of STD control strategies in the United States, discuss the seven components upon which current efforts are based, and speculate about our future programme initiatives.

Anti-Bacterial Agents↗