Probing of active site residues of the zinc enzyme 5-aminolevulinate dehydratase by spin and fluorescence labels

5-Aminolevulinate dehydratase from bovine liver requires Zn(II) for its activity and is inhibited by micromolecular concentrations of Pb(II). To elucidate the structure of the active site and its interactions between the active site and the metal binding site we labeled the active site for fluorescence studies and ESR spectroscopy. o-Phthalaldehyde reacted with active site lysyl and cysteinyl residues to form a fluorescent isoindole derivative. The fluorescence energy was independent of the deprivation of Zn(II) and of its substitution by the inhibitory Pb(II). For ESR-studies five iodoacetamide and four isothiocyanate pyrrolidine-N-oxyl derivatives with various spacer lengths were used to label the active site cysteinyl and lysyl residues, respectively. The ESR spectra of the modified enzyme preparations exhibited a significant immobilization of all labels, even with the longest spacers employed. Obviously the reactive cysteine is buried more than 12 A, and the active site lysine more than 11 A in a cleft of the enzyme structure. Zn(II) deprivation from the iodoacetamide spin-labeled enzyme caused a marked reversible increase in label mobility, whereas the Pb(II) substituted enzyme exhibited a smaller mobilization of the label. These results are interpreted by a model of the active site where the reactive cysteinyl and the lysyl side groups are close enough to be crosslinked by o-phthalaldehyde within a distance of 3 A. A structural role is assigned to Zn(II) in the enzyme, since Zn(II) deprivation does not alter the fluorescence of the isoindole derivative and increases the mobility of the cysteine-bound spin labels in the active site cleft.

Nasal carriage of Staphylococcus aureus: correlation with hormonal status in women

In view of recent observations on hormone-microorganism interactions, a study of Staphylococcus aureus nasal carriage in relation to sex-hormone status was undertaken. Prospectively in 479 women attending a colpocytologic clinic, hormonal status was assessed by determining the karyopyknotic index (KI) on smears stained by the Papanicolaou method. Rates of S. aureus nasal carriage were 29.3% in premenopausal women and 21.9% in postmenopausal women (P not significant). Carriage rates were significantly higher (P = .026, chi 2 7.32) for women with high KIs (40.7%) than for those with intermediate and low KIs (27.03% and 25.1%, respectively). S. aureus nasal carriage also correlated independently and significantly with previous antibiotic use and the presence of insulin-treated diabetes mellitus. This preliminary observation confirms an association between levels of sex hormones as reflected by the KI and S. aureus nasal carriage rates.

An in-use evaluation of decontamination of polypropylene versus steel bedpans

A prospective cross-over study in three different wards has demonstrated the lack of effect of two disinfectants compared with a detergent when added to the washing cycle of automatic bedpan washers that employ hot water centrally supplied at 60 degrees C. An unexpected and potentially important finding was that polypropylene pans were much more effectively cleaned and decontaminated than their stainless steel counterparts. The role, if any, of bedpans in the epidemiology of nosocomial infections remains a mystery. The continued absence of information clearly incriminating these ubiquitous devices in the transmission of potential pathogens, or of genes encoding antibacterial drug resistance, raises questions as to whether extensive efforts to achieve a high degree of decontamination of bedpans are necessary at all.

Pefloxacin versus ceftazidime in therapy of soft tissue infections in compromised patients

Soft tissue infections in compromised patients are frequently caused by Gram-negative organisms and particularly by Pseudomonas aeruginosa. These pathogens are effectively eradicated by pefloxacin as well as by ceftazidime. The effectiveness and safety of these two agents were compared in a prospective randomized study in 67 patients with soft tissue infections. Underlying conditions included malignant diseases, diabetes mellitus and chronic renal failure. The infections included: post operative infection, septic foot, soft tissue abscess and cellulitis. Thirty-three patients were treated with intravenous ceftazidime for a mean duration of ten days. More than half the 34 patients given pefloxacin were treated only orally for a mean period of 13 days. The clinical and bacteriological outcomes were similar in both groups. There was clinical cure or improvement in 26 pefloxacin cases and in 23 ceftazidime cases, failure in six pefloxacin cases and in seven ceftazidime and relapse in two pefloxacin and in three ceftazidime patients. The bacteriological responses were eradication in 23 pefloxacin cases and in 22 ceftazidime cases, persistence in five pefloxacin cases and in six ceftazidime cases, relapse in one pefloxacin case and in none of the ceftazidime group, reinfection in four pefloxacin cases and in three ceftazidime cases and there was one unassessed patient in the pefloxacin group and two in the ceftazidime group. Nausea and vomiting occurred in three patients and elevation of liver enzymes in another patient; all side effects were observed only in the pefloxacin treated patients. These results suggest that oral pefloxacin could offer an alternative to intravenous ceftazidime in half the compromised patients with tissue infections. However, adverse reactions due to pefloxacin administration should be watched for during such therapy.

Two different zinc sites in bovine 5-aminolevulinate dehydratase distinguished by extended X-ray absorption fine structure

The zinc coordination in 5-aminolevulinate dehydratase was investigated by extended X-ray absorption fine structure (EXAFS) associated with the zinc K-edge. The enzyme binds 8 mol of zinc/mol of octameric protein, but only four zinc ions seem sufficient for full activity. We have undertaken a study on four forms of the enzyme: (a) the eight-zinc native enzyme; (b) the enzyme with only the four zinc sites necessary for full activation occupied; (c) the enzyme with the vacant sites of (b) occupied by four lead ions; (d) the product complex between (b) and porphobilinogen. We have shown that two structurally distinct types of zinc sites are available in the enzyme. The site necessary for activity has an average zinc environment best described by two/three histidines and one/zero oxygen from a group such as tyrosine or a solvent molecule at 2.06 +/- 0.02 A, one tyrosine or aspartate at 1.91 +/- 0.03 A, and one cysteine sulfur at 2.32 +/- 0.03 A with a total coordination of five ligands. The unoccupied site in (b), obtained by taking the difference spectrum between the spectra from samples (a) and (b), is dominated by a single contribution of four cysteinyl sulfur atoms at 2.28 +/- 0.02 A. Spectra from samples (c) and (d) show only small changes from that of (b), reflecting a slight rearrangement of the ligands around the zinc atom.

Rapid screening of urine for bacteria and cells by using a catalase reagent

Five hundred urine samples were tested for cells and bacteria by using a commercial dipstick, a catalase screening device, standard culturing, and chamber counts. The sensitivities of the catalase test were 83% for all samples and 97.6% for specimens containing significant numbers of leukocytes and bacteria. The catalase screening test is simple to perform and should prove useful for the detection of urinary tract infections.

Effects of intravenous fat infusion on neonatal neutrophil and platelet function

Intravenous fat (Intralipid) is used extensively as a major component of parenteral nutrition for patients in the neonatal intensive care unit. Abnormalities of polymorphonuclear leukocyte (PMN) and platelet number or function related to Intralipid infusion have been reported although conflicting results exist. In order to examine potential adverse hematologic effects of Intralipid, 10 ill neonates were studied before and after a 16-hr infusion of 1 g/kilo of Intralipid. PMN count, chemokinesis, chemotaxis, and aggregation were unchanged pre- and post intralipid infusion. Platelet count, bleeding time, and platelet aggregation were also unchanged. Similar results were obtained in vitro when neonatal and adult PMNs and platelets were incubated in Intralipid and their function analyzed. These findings suggest that short-term, low-dose Intralipid has no measurable impact on neonatal PMN or platelet activity and support its use in neonates even in the presence of infection or thrombocytopenia.

Apparent effect of immune serum globulin prophylaxis in the military on viral hepatitis incidence in the civilian population in Israel

Since 1969, extensive use of immune serum globulin in the Israel Defence Force for prophylaxis against hepatitis A virus (HAV) infection has produced a sharp decline in the incidence of the disease. However, it is not clear whether this policy has affected the susceptibility of Israeli adults to HAV infection. In this study, we examined the effect of the immunisation policy on the incidence of hepatitis A virus infection in the civilian population in the 15-44 year age group, which includes all those who have completed compulsory military service since vaccination was introduced. The incidence of viral hepatitis in the Jewish civilian population aged 15-44 increased by approximately 50% 3-4 years after the implementation of the immunisation policy. This rise was not seen in the non-Jewish population of the same age nor among Jews aged 45-64. These findings strongly suggest that the immunisation policy in the military prevents both clinical and sub-clinical disease, but has had the effect of producing more susceptible people at an older age in the civilian population.

Rise in the incidence of viral hepatitis in Israel despite improved socioeconomic conditions

The incidence of viral hepatitis (mostly type A) in Israel, an area highly endemic for the disease, was examined between 1951 and 1985. During a period of improved standards of living, the overall reported incidence of the disease increased. In the Jewish population, the age of peak incidence shifted from 1-4 y to 5-9 y; this change is compatible with improved sanitation. However, whereas the absolute incidence declined among children 1-4 y old, it doubled among those 5-9 y old over the same period. The peak incidence in the non-Jewish population remains in children 1-4 y old. One possible explanation for the rise in overall incidence is an increase in the ratio of clinical to subclinical infections due to a shift of peak incidence to an older age group. Seasonal patterns have persisted against a background of changing morbidity, with the maximal incidence from late summer to midwinter. An unexplained, consistent excess incidence among males is observed for all age groups.

Immunoglobulin M, A, and G antibody response to lipopolysaccharide O antigen in symptomatic and asymptomatic Shigella infections

The antilipopolysaccharide antibody response in sera obtained from subjects involved in 10 outbreaks of shigellosis occurring in Israeli military field units was determined by an enzyme-linked immunosorbent assay and a passive hemagglutination test. Both tests were found to be sensitive and specific for the diagnosis of shigellosis. A significant antibody response was detected in 73 to 82% of the symptomatic and 48 to 60% of the asymptomatic subjects during the Shigella sonnei and Shigella flexneri outbreaks. Fifty percent of the symptomatic and none of the asymptomatic subjects showed a significant antibody response in the Shigella boydii outbreaks. An examination of the kinetics of the antibody levels over a 10-week period after the onset of disease revealed that immunoglobulin A (IgA) levels were highest 2 weeks after infection and had declined to initial levels within 2.5 months. In contrast, IgG levels at the late convalescent stage were half those measured at early convalescence, still being about twice as high as the initial titers. Although the IgM levels showed a pattern similar to that of IgA, their elevation at the early convalescent stage was less pronounced. We conclude that the detection of an increase in the level of the IgA fraction appeared to be the best indicator for recent symptomatic, as well as symptomatic, infections due to Shigella organisms.

Prostatic abscess in the antibiotic era

The clinical and bacteriologic features of 269 cases of prostatic abscess (PA) reported during the last 40 years were reviewed. In the pre-antibiotic era, PA not uncommonly had a dramatic presentation and frequently was caused by Neisseria gonorrhoeae. Currently, PA may be difficult to differentiate from prostatitis and other diseases of the lower urogenital tract. Prostatic enlargement is found in 75% of cases, whereas fever and urinary retention each occur in only one-third of cases. The organisms most frequently isolated from PA are Escherichia coli and other gram-negative bacilli; other isolates include Staphylococcus species and an expanding spectrum of bacteria and fungi. PA due to Staphylococcus species may also occur in neonates. Transrectal ultrasonography and computerized tomography are valuable methods for the preoperative diagnosis of PA. Although transurethral resection of the prostate is the most commonly used therapy for PA, transperineal aspiration of pus guided by transrectal ultrasonography appears to be promising.

Pseudomonas stutzeri causing late prosthetic valve endocarditis

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A prospective epidemiologic study of shigellosis in the Israel Defense Forces: implications for the use of shigella vaccines

Recent development of new shigella vaccines has renewed interest in the current epidemiology of shigellosis in endemic regions. A prospective epidemiologic study of 5,774 soldiers was carried out in the Israel Defense Forces, between the months of May and September 1984. Shigellosis was found to be responsible for half the diarrhea epidemics and only rarely presented as sporadic cases of diarrhea. The epidemics occurred after exposure to field conditions, whereas under fixed military base conditions the finding of a case of shigellosis generally was not associated with an epidemic spread of the disease. It was concluded that, in this population, effective shigella vaccines may provide an important means of preventing epidemics of shigellosis in military units operating outside of permanent bases.

Immunogenicity of a single dose of trivalent influenza vaccine including A/Philippines (H3N2): results of a field trial

During 1982, a new A(H3N2) influenza virus subtype, A/Philippines/2/82, was identified, and this strain was combined with previous A(H1N1) and B influenza virus strains in the trivalent inactivated vaccine recommended for the 1983-1984 influenza season. Prior to the widescale use of this vaccine in Israel, a group of 106 young male soldiers was vaccinated under controlled conditions. Before vaccination, antibody titers greater than or equal to 1:40 were found in 14.1% against A/Philippines (H3N2), 18.1% against A/England/333/80 (H1N1), and 13.3% against B/Singapore/222/79. Two weeks following vaccination, 78.9% of the vaccinees for whom repeated blood samples were available, had antibody titers in this range for A/Philippines (H3N2), 92.9% for A/England (H1N1), and 80.0% for B/Singapore. The vaccine was only mildly reactogenic, and there were no cases of absence from work following vaccination. Thus the antibody response of young subjects to a single dose of a vaccine containing a new A(H3N2) subtype was found to be satisfactory, and the side effects experienced were minimal.

Aquarium-borne Mycobacterium marinum skin infection. Report of a case and review of the literature

A 33-year-old fish fancier developed a protracted skin infection that ultimately was found to be caused by Mycobacterium marinum. The organism was isolated from the lesion as well as from infected fish taken from his home aquarium. The lesion resolved after a six-week course of oral sulfamethoxazole and trimethoprim. Forty-four additional cases of culture-proved M marinum skin infections acquired from aquariums and reported in the English-language literature are reviewed. Almost universally, the lesions remained circumscribed and were either single nodular (14 patients) or multiple sporotrichoid (31 patients). Diagnosis was supported by acid-fast smears (15 patients) and isolation of the organism from skin lesions (43 patients) or from fish (two cases). In vitro studies, as well as clinical outcomes, suggest sulfamethoxazole-trimethoprim or ethambutol hydrochloride plus rifampin to be the drugs of choice.

Polymorphonuclear leukocyte adherence and chemotaxis in stressed and healthy neonates

Defects in polymorphonuclear neutrophil (PMN) adherence and chemotaxis in neonates are thought to be an important cause of their increased susceptibility to overwhelming bacterial infection. Few studies of these functions have been carried out in stressed neonates who are at even greater risk of infection. PMN adherence and chemotaxis were examined in 33 stressed neonates with acute lower respiratory illness, 13 healthy neonates, and 43 healthy adults using whole blood PMN adherence and chemotaxis assays. PMN chemotaxis was significantly decreased in stressed neonates (locomotion index of 38.4 +/- 9.7 micron) compared with that of healthy neonates (48.9 +/- 12.8 micron, p less than 0.01) or adults (61.6 +/- 11.9 micron, p less than 0.001). PMN chemotaxis was studied during illness and recovery in 13 of the 33 stressed neonates and showed significant improvement during recovery (41.6 +/- 9.9 and 53.2 +/- 11.9 micron, respectively, p = 0.012). PMN adherence was decreased in stressed neonates (1.4 +/- 1.6%) compared with that of adults (12.3 +/- 11.4%, p less than 0.01) but was similar to that of healthy neonates (1.1 +/- 1.4%). These findings suggest that further impairment of PMN chemotaxis in stressed neonates helps account for their increased susceptibility to overwhelming bacterial infection.

The role of bougienage in the management of achalasia--the need for reappraisal

Passive dilatation, advocated in the past by a number of gastroenterologists as the initial therapy for achalasia, has fallen into disrepute in the last 15 years. Our recent experience with five achalasia patients, four of whom were judged too fragile for esophageal myotomy or forcible dilatation, indicates the need for reappraisal of bougienage therapy.

A multicentre study of the susceptibility of a variety of bacteria to cephalothin, cefamandole, tobramycin and gentamicin

A multicentre study of antibiotic susceptibility was performed in South Africa. Sensitivity to cephalothin, cefamandole, tobramycin and gentamicin was tested on a variety of aerobic and anaerobic bacteria. Two disc susceptibility techniques were used, i.e. the Kirby-Bauer technique (aerobes) and the broth-disc method (anaerobes); minimum inhibitory concentrations (MICs) were determined according to the International Collaborative Study techniques, and regression lines for individual centres were constructed. Satisfactory lines were obtained for cephalosporins, but, in some centres, problems were experienced with the aminoglycosides. Variations in MICs for Haemophilus influenzae were probably due to an inoculum effect. Accumulative percentage tables of the number of strains inhibited were compiled, and the comparative performance of the antibiotics was assessed.