Gender, race, and perception of environmental health risks

This paper reports the results of a national survey in which perceptions of environmental health risks were measured for 1275 white and 214 nonwhite persons. The results showed that white women perceived risks to be much higher than did white men, a result that is consistent with previous studies. However, this gender difference was not true of nonwhite women and men, whose perceptions of risk were quite similar. Most striking was the finding that white males tended to differ from everyone else in their attitudes and perceptions--on average, they perceived risks as much smaller and much more acceptable than did other people. These results suggest that socio-political factors such as power, status, alienation, and trust are strong determiners of people's perception and acceptance of risks.

Effects of nitric oxide synthase inhibitors on murine infection with Mycobacterium tuberculosis

We have recently demonstrated that the macrophage L-arginine-dependent cytotoxic pathway effectively kills the virulent Erdman strain of Mycobacterium tuberculosis in vitro via the generation of toxic reactive nitrogen intermediates by the enzyme nitric oxide synthase. This report demonstrates that two distinct inhibitors of nitric oxide synthase (aminoguanidine and NG-monomethyl-L-arginine) render similar deleterious effects on tuberculous infection in mice, as assessed by mortality, bacterial burden, and pathological tissue damage, thus confirming the importance of reactive nitrogen intermediates in resistance against M. tuberculosis.

Accurate quantification of hepatitis C virus (HCV) RNA from all HCV genotypes by using branched-DNA technology

In studies monitoring disease progression and therapeutic response, it is essential that the method used for hepatitis C virus (HCV) quantification not be influenced by genotypic variability. The branched DNA assay provides a reliable method for the quantification of HCV RNA. A modified set of oligonucleotide probes for the branched DNA assay was developed to enhance the efficiency of binding to genotypic variants of HCV. The improved branched DNA assay (HCV RNA 2.0) yielded highly reproducible quantification of hepatitis C virus RNA and displayed a nearly 600-fold dynamic range in quantification up to 120 Meq of HCV RNA per ml. The quantification limit was set at 0.2 Meg of HCV RNA per ml to ensure a specificity of > or = 95%. With this lowered quantification limit and the enhanced hybridization of the probes, the HCV RNA 2.0 assay exhibited a high level of sensitivity (96%) and was virtually unaffected by the genotypic variability of HCV. The HCV RNA 2.0 assay may be a useful tool for following HCV RNA levels throughout the course of disease, selecting patients for therapy, and evaluating therapeutic response.

Malunited forearm fractures in children

From 1971 to 1986, 80 skeletally immature patients with severe diaphyseal both-bone forearm fractures were treated at Orlando Regional Medical Center. Greenstick, Monteggia, and Galeazzi fractures were excluded. Seventy-nine fractures were managed by closed means. When anatomic reduction could not be obtained, the best position was accepted. There were 47 patients with malunions of whom 39 returned for follow-up evaluation greater than 2 years after injury. They form the basis of this study. There were no delayed unions or nonunions in the entire group. Average follow-up in the group reported was 5 years 9 months (range 2 years to 13 years 10 months). All patients were satisfied with their functional and cosmetic results regardless of age, angulation, complete displacement, or loss of radial bow at time of union. Only nine patients had loss of motion. By our criteria, 36 patients (92%) had good or excellent results, with 32 excellent and four good results. Three patients (8%) had fair results, and there were no poor results. Age at time of injury did not correlate with recovery of motion. Distal fractures were found to have a better prognosis than proximal fractures. Based on the results of this study, closed reduction is the treatment of choice for skeletally immature patients with diaphyseal fractures of the radius and ulna.

Sexual complications of anterior fusion of the lumbar spine

Recently, there is renewed interest in anterior fusion for spondylolisthesis and congenital and paralytic scoliosis with pelvic obliquity. Some of the candidates are prepubertal boys. Sterility after surgery in urogenitally normal prepubertal boys will not be determined until these patients mature. A worldwide survey of 20 surgeons with 15-20 years of experience (4,500 cases) reports the frequency of sterility (retrograde ejaculation) to be 19 cases (0.42%) and impotence 20 cases (0.44%). One-fourth of the retrograde ejaculation cases resolved and became normal. Impotence is non-organic. The complication of retrograde ejaculation does not appear to be related to approach, though it was related to technique. While the complications of sterility and impotence following anterior fusion have been over-exaggerated, caution and informed consent from adult males and parents of prepubertal male children is advisable.

Skeletal myogenesis: the preferred pathway of chick embryo epiblast cells in vitro

The epiblast layer of the chick embryo gives rise to all embryonic tissues. In vitro analyses were carried out to determine whether epiblast cells could form skeletal muscle prior to entry into the primitive streak. Epiblasts were separated from the mesoderm, hypoblast, and primitive streak, dissociated to produce a single cell suspension, and plated at high density. Myogenesis began on the first day in culture, and by the fifth day most cells had differentiated into skeletal muscle. Some cells differentiated without replicating. MyoD messenger RNA was present in epiblast tissue and translated in practically all cells in culture. Cells from regions of the epiblast which do not form muscle later in the embryo did so in vitro. Epiblasts cultured for 2 days as an intact epithelium, or in the presence of the mesoderm and hypoblast, did not undergo myogenesis. These findings demonstrate that myogenic potential is wide-spread within the primitive streak stage epiblast, and that muscle differentiation, which occurs relatively autonomously in culture, can be prevented by cell and tissue interactions.

The dynamics of microbial colonization of barrier membranes for guided tissue regeneration

The microbial colonization of expanded polytetrafluoroethylene membrane by putative periodontopathogens at 3 minutes of intraoral manipulation was determined in 42 patients with 42 mandibular posterior two- to three-wall defects. Twenty patients exhibited no periodontal pockets of > or = 5 mm, other than the study site, and low levels of pathogens (group A). Twenty-two patients revealed multiple periodontal pockets of 5 mm or more and numerous pathogens (group B). Within the preceding 3 months of regenerative surgery, group A patients had received apically positioned flap surgery with osseous recontouring (except for the study site), and group B patients had been enrolled in a non-surgical maintenance program. The subgingival microbiota was examined prior to regenerative therapy, and the membrane microbiota was examined at 3 minutes and at the time of removal at 6 weeks by culture, DNA probes, and phase-contrast microscopy. The mean initial defect depth was 7.4 mm for group A and 7.2 mm for group B. At 6 months, the difference in mean clinical attachment gain was statistically significant (P < 0.001; group A: 3.4 mm; group B: 1.4 mm). At 3 minutes, putative pathogens were detected in seven (16.7%) membranes in group B (group Binfected), and the associated sites gained only 0.6 mm in clinical attachment at 6 months. Clinical attachment gain was modeled as a linear function of the explanatory variables (r2 = 86%). The presence of Porphyromonas gingivalis detected by DNA probe at 3 minutes was associated with 1.5 mm less expected gain (P = 0.0002). Total microbial counts and the percentage of Peptostreptococcus micros and Capnocytophaga species at baseline, and of motile rods on the membrane surface facing the gingiva at 6 weeks, were statistically significant negative predictors of clinical attachment. For each week the membrane remained covered, an additional 0.5 mm gain could be expected (P = 0.002); and for every 10 sites that exhibited bleeding on probing, the clinical attachment gain was 0.6 mm less at the site of regeneration (P < 0.0001). The present results showed that putative pathogens may colonize membranes within 3 minutes of intraoral manipulation. The patient group treated with periodontal osseous surgery revealed the lowest levels of periodontal pathogens in the membranes and exhibited the most gain in clinical attachment.

Endotoxin (LPS) increases mesenteric vascular resistance (MVR) and bacterial translocation (BT)

Endotoxemia is responsible for many of the pathophysiologic alterations that occur with Gram-negative sepsis. We utilized a chronic ovine model to determine the hemodynamic disturbances in the gastrointestinal tract during endotoxemia. Sheep with indwelling arterial, venous, and pulmonary arterial catheters were used. An ultrasonic flow probe was placed on the cephalic mesenteric artery. The animals were subjected to: 1) Ringer's lactate infusion (sham n = 6); or 2) 1.5 mcg/kg E. coli endotoxin (n = 6) over over a period of one half hour and were monitored for 48 hours. They were then sacrificed and specimens of mesenteric lymph node, liver, spleen, kidney, and lung obtained for bacteriologic cultures and histologic analysis. Sheep receiving endotoxin showed more than 50% reduction in the mesenteric blood flow. Mesenteric vascular resistance increased while non-mesenteric systemic vascular resistance decreased. The increase in the total systemic vascular resistance, noted during endotoxemia, was thus likely due to the increase in the mesenteric vascular resistance. At autopsy there were positive cultures for microorganism in the mesenteric lymph nodes in six out of six sheep with endotoxemia as compared to one out of six of control. Thus the vasoconstriction in the mesenteric areas may have resulted in bacterial translocation from the GI tract.

APOE related alterations in cerebral activation even at college age

BACKGROUND

Associations between the APOE genotype and various medical conditions have been documented at a very young age. The association between the APOE genotype and cognitive performance varies at different ages. APOE related changes in brain activation have been recently reported for middle aged and elderly subjects.

OBJECTIVE

To explore APOE related alterations during cognitive activation in a population of young adults.

METHODS

Using H2(15)O positron emission tomography (PET), imaging was carried out in 20 healthy young adults (age 19 to 28 years; four epsilon4 carriers and 16 non-epsilon4 carriers) during a non-verbal memory task. Voxel-wise multiple regression analyses were undertaken, with the activation difference PET counts as the dependent variable and the APOE genotype as the independent variable.

RESULTS

Brain regions were identified where epsilon4 carriers showed significantly lower or higher activation than non-carriers.

CONCLUSIONS

The results suggest that APOE dependent modulation of cerebral flow may be present even at a young age. This may reflect an APOE related physiological heterogeneity which may or may not predispose to brain disease in the ensuing decades or, less likely, the effect of very early Alzheimer's disease related pathological changes.

Effects of plant-derived flavonoids and polyphenolic acids on the activity of mutagens from cooked food

The ability of 3 plant flavonoids (morin, myricetin and quercetin) and 4 polyphenolic acids (caffeic acid, chlorogenic acid, ellagic acid and ferulic acid) to inhibit the genotoxic effects of a number of cooked-food mutagens (IQ, MeIQ, MeIQx, Trp-P-1 and Trp-P-2), was investigated in a bacterial mutation assay using Salmonella typhimurium TA98 as indicator and hepatic S9 mixes from either SWR mice or Syrian hamsters as metabolic activating systems. Although the polyphenolic acids failed to have an effect, the flavonoids generally inhibited IQ, MeIQ, MeIQx and Trp-P-1 induced mutagenesis in a dose-dependent manner, irrespective of the source of S9. This was not the case with Trp-P-2 where the flavonoids were only observed to inhibit when SWR mouse S9 but not Syrian hamster S9 was used. Of the 3 compounds, myricetin and quercetin were superior to morin in their inhibitory capacity.

Nonunion of slightly displaced fractures of the lateral humeral condyle in children: an update

Inadequate treatment continues to be the leading cause of nonunion of slightly displaced fractures of pediatric lateral humeral condyles, despite references to prevention in the orthopaedic literature. In most cases, the elbow was established nonunion can be salvaged by early stabilization and bone grafting, provided that the fragment is in acceptable position and the growth plate of the condylar fragment is open. Procrastination may allow the physis of the condylar fragment to close prematurely, preemptying the golden opportunity to salvage the child's elbow. The author has collected 23 similar cases from correspondence with 17 orthopaedic surgeons.

Protection against Staphylococcus aureus mastitis in dairy cows using a bismuth-based teat seal containing the bacteriocin, lacticin 3147

We assessed the effectiveness of a novel dry cow treatment containing lacticin 3147 using deliberate challenge studies in lactating cows. Infection-free quarters of lactating cows were infused with Teat seal (Cross Vetpharm Group, Ltd., Dublin, Ireland) combined with the food-grade bacteriocin, lacticin 3147. Natural infection of the teat was simulated by deliberately introducing Staphylococcus aureus into the teat duct and teat sinus. Relative to control quarters, teat seal plus lacticin 3147 reduced the number of teats shedding viable cells when an inoculum of either approximately 1.7 x 10(3) or approximately 6.8 x 10(3) cfu per teat was used. In addition, the numbers of challenge organisms in those teats from which S. aureus was subsequently recovered were also reduced. However, when the concentration of bacteriocin in the teat seal formulation was reduced by approximately 50%, the number of teats shedding S. aureus cells was not reduced. These data indicate the potential for lacticin 3147 to prevent staphylococcal mastitis infections when a sufficient concentration of the bacteriocin is present. This study also highlights the application of a lactating-cow model to assess the effectiveness of antimicrobial intramammary products on mastitic cell populations.

A complex bilateral polysyndactyly disease locus maps to chromosome 7q36

We demonstrated that the gene responsible for a congenital limb deformity (polysyndactyly) maps to chromosome 7q36 in a large family. Pre- and postaxial anomalies of the extremities are inherited in this family as an autosomal dominant trait. The disease locus is closely linked to D7S550 (maximum lod score = 6.85, theta = 0). This region is homologous to a segment of mouse chromosome 5, where the mutations hammer toe (HM) and hemimelic extra toes (HX) have been mapped. These data suggest that human chromosome 7q36 and the homologous region of mouse chromosome 5 contain genes involved in limb pattern formation.

Murine DNA cytosine-C5 methyltransferase: pre-steady- and steady-state kinetic analysis with regulatory DNA sequences

We present the first description of KmDNA, KdDNA, Kcat, and Kmethylation for a mammalian DNA methyltransferase. Homogeneous, 190 000 MTDNA (cytosine-5-)-methyltransferase isolated from mouse erythroleukemia cells has turnover constants of 0.15-0.59 h-1 with single-stranded and unmethylated double-stranded oligonucleotides containing a single CpG dinucleotide. These substrates were designed to mimic DNA transcriptional cis elements previously reported to have cytosine C-5-methylated regulation. The rate-limiting step for these substrates is the methylation step itself. In contrast, hemimethylated double-stranded substrates show burst kinetics, consistent with a rapid methylation event (3 h-1) followed by a slower step which determines steady-state Kcat. Hemimethylated and unmethylated double-stranded DNA shows similar binding affinities; these results reveal the molecular basis for the enzyme's preference for hemimethylated DNA to be the methyl transfer step. Substrates with multiple recognition sites do not show burst kinetics and have turnover rate constants of 6 h-1. Catalytic turnover for the mammalian enzyme is thus approximately 10-fold slower than that for the related bacterial enzymes. Our combined results show quantitatively that one enzyme is certainly capable of both maintenance and de novo methylation and that maintenance of the genomic methylation pattern is preferred over the de novo establishment of new patterns. Direct comparison of the mammalian enzyme with the bacterial DNA cytosine-C5 methyltransferase, M.SssI, indicates dramatic differences in preferences for single-stranded, double-stranded, and hemimethylated double-stranded substrates. Moreover, the specificity hierarchy shown for the M.SssI is derived from very different changes in K(m) and catalysis than those observed for the mammalian DCMTase. These results demonstrate that the M.SssI, and perhaps other DNA cytosine methyltransferases from bacteria, is functionally dissimilar to the mammalian enzyme.

The effect of various dietary fibres on tissue concentration and chemical form of mercury after methylmercury exposure in mice

The whole-body retention of mercury after exposure of BALB/c mice to methylmercury was measured in animals fed fibre-free, 5% pectin, 5% cellulose or 5, 15 or 30% wheat bran diets. The rate of elimination of mercury was dependent on the diet fed, with dietary bran increasing the rate of elimination. The incorporation of 15 or 30% bran in the diet of the mice decreased the total mercury concentration in the brain, blood and small intestine, although the effects were significant only in those animals on 30% bran diet. The fibres had little effect on mercury levels in other tissues. The proportion of mercury found in the mercuric form was significantly greater in liver, kidneys and gut of mice fed bran. The results suggest that dietary bran may reduce the levels of mercury in the brain after methylmercury exposure and may therefore reduce the neurotoxic effects of the organomercurial. We suggest that wheat bran exerts its effects on mercury retention and brain level via a modification of the metabolic activity of the gut microflora.

A serum-free medium for testing fermentation reactions in Neisseria gonorrhoeae

Gonococcal infections can no longer be considered exclusively urogenital but it is difficult in a busy routine laboratory to identify gonococci from non-genital sites, especially if other commensal neisseria are present. Unfortunately, conventional serum agar sugars sometimes give equivocal results. A fermentation medium is described for the identification of gonoccoci. On preliminary testing this medium gives rapid and reliable results and should prove to be much more helpful to the routine laboratory than conventional serum agar sugars. Its potential usefulness, as demonstrated by the results of our first 200 examinations, would seem to justify further study in the routine work of other laboratories.

A quantitative study of stage-specific spermatocyte damage following administration of ethylene glycol monomethyl ether in the rat

A quantitative study has been carried out to characterize the stage susceptibility of the spermatocyte to ethylene glycol monomethyl ether (EGM) toxicity. EGM was administered as a single oral dose of 250 mg/kg body wt and rats were examined at time periods after dosing. The number of spermatocytes and round spermatids in tubules at each stage of spermatogenesis was counted. A sharp transition in susceptibility was observed between zygotene spermatocytes in stage XIV which showed no effect and pachytene spermatocytes in stage I which showed death or depletion of 70% of its population after 1 day. A similar transition was seen between dividing spermatocytes and step 1 spermatids, the latter being unaffected. There was a gradual reduction in susceptibility toward midpachytene such that cells in stages VII-XI showed no effect. Analysis of later time periods revealed no effect on spermatogonia or prepachytene spermatocytes but did indicate that midpachytene spermatocytes underwent delayed cell death after further progression through the cycle. In a separate sequential morphological study of early changes, the earliest signs of necrosis were seen 12 hr after dosing and were restricted to spermatocytes in stages V, XI, and XII. Cell death then progressed in a wave-like manner through stages XIII and XIV finally reaching stage I, 24 hr after dosing.

Reconciling structure and function in HhaI DNA cytosine-C-5 methyltransferase

Pre-steady state partitioning analysis of the HhaI DNA methyltransferase directly demonstrates the catalytic competence of the enzyme.DNA complex and the lack of catalytic competence of the enzyme.S-adenosyl-L-methionine (AdoMet) complex. The enzyme.AdoMet complex does form, albeit with a 50-fold decrease in affinity compared with the ternary enzyme.AdoMet.DNA complex. These findings reconcile the distinct binding orientations previously observed within the binary enzyme.AdoMet and ternary enzyme. S-adenosyl-L-homocysteine.DNA crystal structures. The affinity of the enzyme for DNA is increased 900-fold in the presence of its cofactor, and the preference for hemimethylated DNA is increased to 12-fold over unmethylated DNA. We suggest that this preference is partially due to the energetic cost of retaining a cavity in place of the 5-methyl moiety in the ternary complex with the unmethylated DNA, as revealed by the corresponding crystal structures. The hemi- and unmethylated substrates alter the fates and lifetimes of discrete enzyme.substrate intermediates during the catalytic cycle. Hemimethylated substrates partition toward product formation versus dissociation significantly more than unmethylated substrates. The mammalian DNA cytosine-C-5 methyltransferase Dnmt1 shows an even more pronounced partitioning toward product formation.

Erythrocyte survival following intraoperative autotransfusion in spinal surgery: an in vivo comparative study and 5-year update

A 5-year prospective study of intraoperative blood transfusion in 239 patients, most of whom had major spinal surgery, has been completed. Autotransfusion is safe, practical, and it reduces donor blood requirements and total blood loss by 50%. It eliminates host versus graft reactions and disease transmission. In 33 patients having major spinal surgery, the in vivo survival of autologous, homologous, and processed red blood cells (RBC) using the Cell Saver System were compared. The RBC survival studies were performed using chromium51 isotope labeling technique. The long-term survival of processed RBCs was normal over a 30-day period. There was no significant difference in the survival rate of the three groups studied.

Molecular identification of Dialister pneumosintes in subgingival plaque of humans

Dialister pneumosintes is a nonfermentative, anaerobic, gram-negative rod that grows with small, circular, transparent, shiny, smooth colonies on blood agar. Even though D. pneumosintes has been recovered from deep periodontal pockets, little is known about the relationship between the organism and destructive periodontal disease. This study describes a rapid PCR method to identify D. pneumosintes in periodontal samples. The PCR identification method detected as little as 10 pg of D. pneumosintes DNA or about 1 to 10 cells without nonspecific amplification of various periodontopathic bacteria. Twelve of 22 subgingival samples from adult periodontitis lesions yielded D. pneumosintes either by culture or by PCR identification. In culture-positive samples, D. pneumosintes averaged 3.9% (0.001 to 10.8%) of total isolates. Studies are needed to delineate virulence factors of D. pneumosintes pertinent to periodontal disease.

Depletion of L3T4+ and Lyt-2+ cells by rat monoclonal antibodies alters the development of adoptively transferred experimental autoimmune thyroiditis

To delineate the contribution of L3T4+ and Lyt-2+ cells in the pathogenesis of experimental autoimmune thyroiditis (EAT), synergistic pairs of monoclonal antibodies (mAb) to the T cell subsets were used in conjunction with the adoptive transfer of mouse thyroglobulin (MTg)-activated cells from immunized mice. Initial experiments verified the important role of L3T4+ cells in the transfer of EAT. Subsequent experiments pointed to the relative contribution of both L3T4+ and Lyt-2+ cells, depending on the stage and extent of disease development. Treatment during disease with L3T4, but not Lyt-2, mAb alone significantly reduced thyroiditis. However, in situ analysis of the cellular infiltrate in thyroid sections revealed that, after treatment with mAb, the appropriate subset was eliminated without altering the amount of the other subset in the remaining lesion. In addition, treatment during severe thyroiditis following the transfer of MTg-activated lymph node cells showed that Lyt-2 mAb alone also reduced thyroid infiltration. When the recipients were pretreated with either pair of mAb before transfer, disease development was only moderately affected. We conclude that (i) donor L3T4+ cells are the primary cells responsible for the initial transfer and development of thyroiditis; and (ii) previous in vitro cytotoxicity data, plus current monoclonal antibody treatment of disease and in situ analysis, further implicate a role for Lyt-2+ cells in EAT pathogenesis.