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Biomedical subjects

B Schwartz

Publications and source records attributed to B Schwartz.

At least 199 records · Page 11Linked to original sources
PubMed1993

A nosocomial pseudo-outbreak of Mycobacterium xenopi due to a contaminated potable water supply: lessons in prevention.

OBJECTIVES: To determine risk factors for Mycobacterium xenopi isolation in patients following a pseudo-outbreak of infection with the organism. DESIGN: Retrospective cohort analysis of mycobacteriology laboratory specimen records and frequency-matched case-control study of hospital patients. SETTING: General community hospital. PATIENTS: For the case-control study, 13 case patients and 39 randomly selected controls with mycobacterial cultures negative for M xenopi, frequency matched by specimen source, whose specimens were submitted from June 1990 through June 1991. RESULTS: Between June 1990 and June 1991, M xenopi was isolated from 13 clinical specimens processed at a midwestern hospital, including sputum (n = 6), bronchial washings (2), urine (4), and stool (1). None of the patients with M xenopi-positive specimens had apparent mycobacterial disease, although five received antituberculosis drug therapy for a range of one to six months. Specimens collected in a nonsterile manner were more likely to grow the organism than those collected aseptically (3.1% versus 0, relative risk = infinity, P = 0.003). M xenopi isolation was attributed to exposure of clinical specimens to tap water, including rinsing of bronchoscopes with tap water after disinfection, irrigation with tap water during colonoscopy, gargling with tap water before sputum collection, and collecting urine in recently rinsed bedpans. M xenopi was isolated from tap water in 20 of 24 patient rooms tested, the endoscopy suite, and the central hot water mixing tank, but not from water in the microbiology laboratory. The pseudo-outbreak occurred following a decrease in the hot water temperature from 130 degrees F to 120 degrees F in 1989. CONCLUSIONS: Maintenance of a higher water temperature and improved specimen collection protocols and instrument disinfection procedures probably would have prevented this pseudo-outbreak.

Adult↗
PubMed1993

Outbreak of pyogenic abscesses after diphtheria and tetanus toxoids and pertussis vaccination.

Nine children who received diphtheria and tetanus toxoids and pertussis vaccine from the same vial at a clinic in Colorado developed pyogenic abscesses at the site of injection. Eight abscesses required surgical drainage and five children were hospitalized. Group A Streptococcus (GAS) was cultured from eight wounds and Staphylococcus aureus was also isolated from four. Epidemiologic investigation revealed that within the hour of the first child's vaccination, three children had been diagnosed in the clinic with GAS pharyngitis. GAS recovered from repeat throat swabs from two of these children and the eight case-isolates were all serotype M-12, T-12 and had identical immunoblot patterns on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Laboratory simulation studies demonstrated that GAS can survive for at least 4 days on the external surface of a vaccine vial rubber stopper and contaminate needles inserted through the stopper. Swabbing the stopper with 70% isopropyl alcohol resulted in effective disinfection. To prevent potential contamination meticulous attention to sterile technique is important when withdrawing vaccine from multidose vaccine vials.

1-Propanol↗
PubMed1993

Use of nasopharyngeal isolates of Streptococcus pneumoniae and Haemophilus influenzae from children in Pakistan for surveillance for antimicrobial resistance.

Antimicrobial resistance of Streptococcus pneumoniae and Haemophilus influenzae presents a challenge to clinical case management, particularly in programs for acute respiratory tract infection (ARI), including pneumonia, in developing countries. To determine whether nasopharyngeal isolates of S. pneumoniae and H. influenzae from a clinically defined group of children could be used to predict the prevalence of antimicrobial resistance of strains that cause disease, 601 urban children with ARI, 133 healthy urban children and 285 rural children were evaluated in Pakistan. Of the urban children with ARI, 216 (35.9%) were bacteremic, predominantly with S. pneumoniae (108 children) and H. influenzae (100 children). Overall 631 (61.9%) children carried S. pneumoniae and 381 (37.4%) carried H. influenzae. The proportions of nasopharyngeal isolates of both organisms from urban children with ARI resistant to penicillin or ampicillin, trimethoprim/sulfamethoxazole, chloramphenicol and erythromycin were similar to the proportions of resistant blood isolates. Nasopharyngeal isolates from rural children had lower rates of resistance to some antimicrobial agents. These findings suggest that nasopharyngeal isolates of S. pneumoniae and H. influenzae from children with ARI can be used to conduct surveillance for antimicrobial resistance in a defined geographic area. Such surveillance would aid programs in developing countries in making a rational choice of antimicrobial agents for use in clinical management of bacterial diseases, including pneumonia.

Acute Disease↗
PubMed1993

Differences of retinal nerve fiber layer thickness between normal and glaucoma-like optic disks (physiological cups) matched by optic disk area.

We matched by disk area size 23 eyes of patients with glaucoma-like disks (physiological cups) with normal ocular pressures and no visual field loss with 23 eyes of normal subjects. Using stereophotogrammetry we found a significant decrease in retinal nerve fiber layer thickness in the eyes with glaucoma-like disks compared to the normal eyes (P = 0.0081), especially in the nasal quadrant (18.1%). A similar significant decrease was noted in the neuroretinal rim area and a significant increase in cup volume, area, depth and slope for the total disk and its quadrants. The use of computerized image analysis also showed a significant increase in pallor area for glaucoma-like disks compared to normal disks. Eyes with glaucoma-like disks or physiological cups showed evidence of an optic neuropathy and may be manifesting the same damage to the optic nerve occurring in high pressure open angle glaucoma.

Aged↗
PubMed1993

Three-dimensional evaluation of optic disc pallor in open angle glaucoma.

We evaluated the extent of pallor on the walls of the optic cup three-dimensionally using simultaneous stereophotographs of the optic discs of 29 normals, 29 ocular hypertensives and 28 primary open angle glaucomas. Pallor was located at the bottom of the optic cup. Pallor ascends the walls of the cup as its extent increases. Statistically significant differences in the extent of pallor in all four quadrants of the optic cup were observed, with the glaucomas having greater extents of pallor than ocular hypertensives, and the ocular hypertensives greater than the normals. The greatest percentage increase in mean pallor from normals to open angle glaucomas occurred on the nasal and inferior walls. This differential extent of pallor could be useful in characterizing ocular hypertension and chronic open angle glaucoma.

Adult↗
PubMed1993

Association of phenotypic and genotypic characteristics of invasive Streptococcus pyogenes isolates with clinical components of streptococcal toxic shock syndrome.

Sixty-two invasive Streptococcus pyogenes strains, including 32 strains isolated from patients with streptococcal toxic shock syndrome (STSS), were analyzed for the following phenotypic and genotypic characteristics: M-protein type, serum opacity factor production, protease production, the presence of streptococcal pyrogenic exotoxin (Spe) genes A, B, and C, and in vitro production of SpeA and SpeB. These characteristics were analyzed for possible associations with each other as well as with clinical components of STSS. M-type 1, the most commonly isolated M-type, was significantly associated with protease production. Protease activity was significantly associated with the clinical sign of soft tissue necrosis. M-type 1 and 3 strains from STSS patients were significantly associated with the clinical signs of shock and organ involvement as well as with SpeA production in vitro. Finally, the production of SpeA was significantly associated with the clinical component of shock and organ involvement as well as with rash. These data suggest that STSS does not make up a single syndrome but, rather, that the multiple STSS clinical criteria probably reflect different phenotypic characteristics of individual S. pyogenes isolates.

Adolescent↗
PubMed1993

Health-care lighting.

Explore the source record for details and available documents.

Hospital Design and Construction↗
PubMed1992

Structural analysis of the human interferon gamma receptor: a small segment of the intracellular domain is specifically required for class I major histocompatibility complex antigen induction and antiviral activity.

Mutations of the human interferon gamma (IFN-gamma) receptor intracellular domain have permitted us to define a restricted region of that domain as necessary for both induction of class I major histocompatibility complex antigen by IFN-gamma and protection against encephalomyocarditis virus. This region consists of five amino acids (YDKPH), all of which are conserved in the human and murine receptors. Tyr-457 and His-461 are essential for activity. Approximately 80% of the amino acids of the intracellular domain of the receptor is not required for major histocompatibility complex class I antigen induction or for antiviral protection against encephalomyocarditis virus. The observation that there was no protection by IFN-gamma against vesiculostomatitis virus indicates that other factors, in addition to chromosome 21 accessory factor(s), are required to generate the full complement of transduction signals from the human IFN-gamma receptor.

Amino Acid Sequence↗
PubMed1992

Prevention of Lyme disease after tick bites. A cost-effectiveness analysis.

BACKGROUND: In areas of endemic disease, the probability of Lyme disease after a tick bite ranges from about 0.012 to 0.05. Early treatment with oral antibiotics prevents most complications of Lyme disease, but antibiotics are generally not prescribed until rash or other symptoms develop. METHODS: We used decision analysis to evaluate the outcomes, costs, and cost effectiveness of three alternative strategies to treat patients bitten by ixodes ticks in areas of endemic Lyme disease: empirically treat all patients with two weeks of doxycycline, treat only patients in whom erythema migrans develops, and treat only patients with erythema migrans or a positive serologic test for Lyme disease one month after exposure. RESULTS: Empirical treatment is the least expensive strategy and results in the fewest cases of Lyme disease and the fewest complications when the probability of Borrelia burgdorferi infection after a tick bite is 0.036 or higher. For probabilities of infection below 0.036, empirical therapy prevents most major complications, sequelae, and adverse events, but it incurs additional minor complications, especially as the probability of infection falls below 0.01. CONCLUSIONS: Empirical treatment of patients with tick bites is indicated when the probability of B. burgdorferi infection after a bite is 0.036 or higher, and this treatment may be preferred when the probability of infection ranges from 0.01 to 0.035. When the probability of infection after a tick bite is less than 0.01, empirical therapy is not warranted.

Animals↗
PubMed1992

The role of mucin in colon-cancer metastasis.

Mucinous colorectal cancer often presents at an advanced stage. We have previously observed that mucin production by human colon-cancer cells correlates with their ability to colonize the liver in experimental animal models. The present study was undertaken in order to further elucidate the mechanisms by which production of mucin by colon-cancer cells affects metastasis. Cell lines showing high mucin production (HMP) (HM 7, HM 3 and LS LiM 6) demonstrated increased adherence to basement membrane proteins and invaded a reconstituted basement membrane to a greater extent than their counter-part cell lines showing low mucin production (LMP) (LS174T and LM 12). Adherence of the LMP parental cell line LS174T to various matrix proteins was potentiated by the addition of purified human colon-cancer mucin in a dose-dependent fashion. HMP cell lines secreted more proteolytically active type-IV collagenase than LMP lines, and collagenase activity was further stimulated by purified mucin in a dose-dependent manner. Specific inhibition of mucin O-glycosylation by benzyl-alpha-N-acetylgalactosamine significantly affected each of the metastasis-related events, with the greatest effect on the HMP cell lines. The present data further indicate that mucin may play an important role in the metastatic process.

Animals↗
PubMed1992

Retinal vessel autoregulation in sickle cell patients.

We tested retinal vessel autoregulation in 16 sickle cell patients and 6 controls by computer-assisted measurements of constriction of the superior and inferior temporal veins and arteries after pure oxygen breathing. Compared to the controls and corrected for age, we found a decrease of vasoconstriction in three of the four vessels measured in the sickle cell group, which was statistically significant only for the superior temporal artery (P 0.009). The number of patients was too small to allow a separate analysis of possible contributory factors within the sickle cell group, such as sickle cell hemoglobin subtype and extent of retinal ischemia. Our findings indicate a factor not yet well known in the pathophysiology of sickle cell disease: an abnormality of local microvascular control.

Adult↗
PubMed1992

Neuroretinal rim area measurements by configuration and by pallor in ocular hypertension and glaucoma.

PURPOSE: The purpose of this study is to examine the differences between measurements of neuroretinal rim area of the optic disc defined by configuration and by pallor. METHODS: One hundred seventy-one patients were studied (59 with glaucoma, 96 ocular hypertensive patients, and 16 controls). The magnification-corrected neuroretinal rim area was measured from black-and-white stereoscopic paper prints. The central area of pallor was measured using computer-assisted image analysis techniques. The percentage of central area of pallor was converted into mm2, and an estimate of neuroretinal rim area defined by color was calculated. RESULTS: The correlation between the measurements of neuroretinal rim area by configuration and by pallor was statistically highly significant (r = 0.89, P less than 0.0001). No consistent differences between measurements were found in different diagnostic groups, or in different stages or types of glaucomatous optic disc abnormality. The correlation of changes of both measurements during a 9-year follow-up period also was statistically significant (r = 0.68, P less than 0.001). CONCLUSION: In clinical routine measurements of the neuroretinal rim area, using both configuration and pallor definition does not seem to add to the information.

Adult↗
PubMed1992

Role of the temporal cilioretinal artery in retaining central visual field in open-angle glaucoma.

The authors reviewed the optic disc photographs of 34 eyes with high-pressure open-angle glaucoma with advanced visual field loss. Thirteen eyes (38%) had one or two temporal cilioretinal arteries, and 21 eyes (62%) had no temporal cilioretinal artery. All 13 eyes with a temporal cilioretinal artery retained central visual field and had visual acuity of 20/40 or better. In the 21 eyes without a temporal cilioretinal artery, 8 eyes lost central visual field and 12 eyes had a visual acuity of less than 20/40, while 13 eyes retained central visual field and 9 eyes had a visual acuity of 20/40 or better. Significant differences were obtained when eyes with and without cilioretinal arteries were compared for retention of visual field (P less than 0.02) and visual acuity (P less than 0.01). The presence of a temporal cilioretinal artery may provide more circulation to the temporal rim of the optic disc and aid in retaining central field and visual acuity in advanced open-angle glaucoma.

Aged↗
PubMed1992

Engineered disulfide bond greatly increases specific activity of recombinant murine interferon-beta.

Unlike other species of interferon-beta (IFN-beta) mouse (Mu) IFN-beta has no naturally occurring intramolecular disulfide bond. When expressed in Escherichia coli, MuIFN-beta appears to exhibit instability and low activity. To increase its activity, we engineered a pair of cysteines into recombinant MuIFN-beta to test whether this change would improve its antiviral activity. In the absence of detailed structural data, the optimal placement of cysteines was determined by sequence comparison with other species of IFN-beta. While MuIFN-beta has only a single cysteine (at position 17), other species of IFN-beta have three cysteines, at positions 17, 31, and 141 (numbering based on consensus sequence), a disulfide bond being formed between the latter two residues. Thus, we introduced cysteines into MuIFN-beta at positions 29 and 136, which correspond to positions 31 and 141 of the consensus sequence. When the variant form of MuIFN-beta was expressed in bacteria and purified, we found that the additional cysteines greatly increased the antiviral activity. Further improvement was obtained by replacement of the Cys-17 with a serine. In this manner a specific activity approximately 15-fold that of the wild-type recombinant molecule was achieved.

Animals↗