Antibody binding regions on human nerve growth factor identified by homolog- and alanine-scanning mutagenesis

The binding specificities of a panel of mouse monoclonal antibodies (MAbs) to human nerve growth factor (hNGF) were determined by epitope mapping using chimeric and point mutants of NGF. Subsequently, the MAbs were used to probe NGF structure-function relationships. Six MAbs, which recognize distinct or partially overlapping regions of hNGF, were evaluated for their ability to block the binding of hNGF to the TrkA and p75 NGF receptors in various in vitro assays, which included blocking of TrkA autophosphorylation and blocking of NGF-dependent survival of dorsal root ganglion sensory neurons. Three MAbs (911,912,938) were potent blockers of all activities. Potent blocking of p75 binding occurs only with MAb 909, which recognizes an NGF region identified by mutagenesis as important for NGF-p75 binding. These results are consistent with recently proposed models of binding regions involved in NGF-TrkA and NGF-p75 interactions generated through mutagenic analysis and structure determination of the NGF-TrkA complex. These studies provide insight to the epitope specificities and potency of MAbs that would be useful for physiological NGF blocking studies.

Unsuspected Pneumocystis carinii pneumonia at presentation of severe primary immunodeficiency

BACKGROUND

Pneumocystis carinii is an important pathogen in immunodeficiency but may be an unrecognised cause of respiratory compromise.

OBJECTIVES

To ascertain the incidence of P carinii pneumonia (PCP) at presentation of severe combined immunodeficiency (SCID), whether it had been diagnosed, and the effect of treatment on outcome.

SETTING

The supraregional paediatric bone marrow transplant unit for primary immunodeficiencies at Newcastle General Hospital.

METHODS

Retrospective case note review of infants referred with a diagnosis of SCID from 1992 to 1998.

RESULTS

Ten of 50 infants had PCP at presentation; only one was diagnosed before transfer. Eight were diagnosed by bronchoalveolar lavage and two by lung biopsy. In only one was P carinii identified in nasopharyngeal secretions. Five required ventilation for respiratory failure but all were successfully treated with co-trimoxazole and methylprednisolone with or without nebulised budesonide. Nine survived to bone marrow transplantation and four are long term survivors after bone marrow transplantation; no deaths were related to PCP.

CONCLUSIONS

PCP is a common presenting feature of SCID but is rarely recognised. Bronchoalveolar lavage or lung biopsy are needed for diagnosis. Treatment with co-trimoxazole is highly successful.

Pseudomonas aeruginosa infection in an intrathecal baclofen pump: successful treatment with adjunct intra-reservoir gentamicin

OBJECTIVE

To describe the use of intra-reservoir gentamicin for the treatment of a Pseudomonas aeruginosa infected baclofen pump.

SETTING

Regional Spinal Injuries Centre, Hexham, Northumberland, England.

SUBJECT

Male patient aged 32 years with progressive multiple sclerosis and severe bilateral spasticity.

RESULTS

Intra-reservoir gentamicin proved successful in treating infection with Pseudomonas aeruginosa.

CONCLUSION

Intra-reservoir gentamicin may be successful in treating pump infection with Pseudomonas aeruginosa without the need for pump removal.

Comparison of PCR detection of mecA with methicillin and oxacillin disc susceptibility testing in coagulase-negative staphylococci

The provisional BSAC method for the detection of methicillin sensitivity in coagulase-negative staphylococci (CNS) requires incubation of isolates for 48 h and raises the problem of timely reporting of susceptibility data. The forthcoming withdrawal of methicillin raises another difficulty. We evaluated 42 clinically significant CNS blood culture isolates by PCR, methicillin and oxacillin disc testing and by using methicillin Etests. Our results suggest that, although oxacillin disc susceptibility testing is a reasonable first line step, optimal and timely detection of resistance or susceptibility may require a combination of phenotypic and genotypic methods.

Atypical presentation of dissection of the ascending aorta in young men with cystic medial necrosis: MR findings

Dissection of the ascending aorta is usually associated with severe chest and/or back pain. We describe three young men, with pathologically proven cystic medial necrosis, who presented with atypical clinical symptoms and ascending aortic dissection diagnosed by MR imaging and surgery. Patients with cystic medial necrosis and aortic dissection may not present with a classic acute chest pain syndrome.

Survival following group A streptococcal septicaemia in a centenarian

We report a case of a centenarian who survived group A streptococcal septicaemia without complications. We would be interested to hear if this patient is the oldest survivor of group A streptococcal septicaemia in the U.K.

Neisseria gonorrhoeae in Newcastle upon Tyne 1995-1997: increase in ciprofloxacin resistance

Fluoroquinolones and third generation cephalosporins are the most effective antimicrobial agents for the treatment of gonorrhoea. However, clinically significant resistance to fluoroquinolones in Neisseria gonorrhoeae has been reported worldwide including Britain. The aim of this analysis was to study the factors relating to ciprofloxacin resistance and treatment failure. A total of 201 patients attending the Newcastle Genitourinary Medicine (GUM) clinic from 1995-1997 who were diagnosed with culture positive gonorrhoea was analysed. Treatment failure rates for ciprofloxacin were determined and the minimum inhibitory concentration (MIC) was measured for all cases of treatment failure. The case notes of all patients who had strains with MICs of ciprofloxacin in the resistant range (>0.05 microg/ml) were reviewed to determine the clinical outcome. The ciprofloxacin resistance with treatment failure was seen in 5% (8/160). All the 8 cases of treatment failure were heterosexual and had isolates resistant to penicillin and 4 cases (50%) were also resistant to tetracycline. All were sensitive to spectinomycin and ceftriaxone. Most of the cases probably acquired their infection from the Far East. As ciprofloxacin resistance seems to be associated with overseas exposure, changes in the standard treatment of gonorrhoea are not justified but consideration should be given to appropriate alternatives when the infection may have arisen from where such resistant strains are endemic. Monitoring fluoroquinolone resistance is now essential for ensuring adequate treatment of infections with resistant strains and for maximizing the time of usage of fluoroquinolones to treat gonorrhoea.

Inhibition of endothelial cell migration by gene transfer of tissue inhibitor of metalloproteinases-1

BACKGROUND

Angiogenesis requires degradation of the vessel's basal lamina and endothelial cell migration into the tissue stroma. Matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) play important roles in this process. MMP activity is tightly regulated during vessel growth. This work was designed to characterize the effect of TIMP-1 upregulation on endothelial cell invasion of the extracellular matrix.

METHODS

We constructed replication-deficient recombinant adenoviruses that encode either TIMP-1 (Ad.TIMP-1) or Escherichia coli lac Z (Ad.beta gal) cDNA. Bovine aortic endothelial (BAE) cells were infected with 100 infectious particles/cell. Gene expression was assessed by Northern and Western blotting. TIMP-1 activity in cell-conditioned media was measured by a resorufin-labeled casein protease assay. BAE cell migration was measured by Boyden chamber assays with 0.2% gelatin-coated, 8. 0-mcm polycarbonate membranes.

RESULTS

TIMP-1 was overexpressed by Ad.TIMP-1-infected BAE cells relative to control, Ad. beta gal-infected or uninfected cells. TIMP-1 activity in Ad.TIMP-1 cell-conditioned medium was 2.8-fold higher than in control cells. By Boyden chamber assays with gelatin-coated membranes, Ad. TIMP-1-infected BAE cells showed 89.97 +/-1.64% (mean +/- SEM) reduction in migration relative to Ad.beta gal-infected cells (P < 0. 02) and 90.53 +/- 1.12% relative to uninfected cells (P < 0.02). Without gelatin coating, migration was equivalent in all groups.

CONCLUSION

The replication-deficient recombinant adenovirus we constructed affords rapid and efficient upregulation of functional TIMP-1 in endothelial cells. Infection results in a dramatic decrease in cell migration and invasion of extracellular matrix. Thus, such a recombinant vector may provide a useful tool for the gene therapy of vascular remodeling and inhibition of angiogenesis.

Stromelysin 1, neutrophil collagenase, and collagenase 3 do not play major roles in a model of chondrocyte mediated cartilage breakdown

AIMS

To determine the collective roles of stromelysin 1, neutrophil collagenase, and collagenase 3 in chondrocyte mediated cartilage proteoglycan and type II collagen degradation in tissue culture model systems.

METHODS

Bovine nasal cartilage explants were cultured with and without recombinant human interleukin 1 alpha (IL-1 alpha), recombinant human tumour necrosis factor alpha, or retinoic acid. Proteoglycan and type II collagen release were determined by colorimetric assay and immunoassay, respectively, in the absence and presence of matrixin inhibitors. Potential toxic effects of the inhibitors were assessed by measuring rates of glycolysis.

RESULTS

Loss of proteoglycan and type II collagen from nasal cartilage was inhibited by batimastat, a broad spectrum matrixin inhibitor. BB-3437, a selective inhibitor of stromelysin, neutrophil collagenase, and collagenase 3, at the concentrations used in this study, showed a weak but dose dependent inhibitory effect on the IL-1 stimulated degradation of type II collagen, but had virtually no effect on proteoglycan breakdown. Neither inhibitor affected rates of glycolysis.

CONCLUSIONS

Stromelysin 1, neutrophil collagenase, and collagenase 3 are unlikely to contribute to chondrocyte mediated proteoglycan degradation in our model system. The modest effect of a selective inhibitor of these enzymes on IL-1 stimulated collagen breakdown suggests a minor role for one or more of these proteinases; potent inhibition by an inhibitor of interstitial collagenase and the gelatinases suggests that these enzymes play a major role in IL-1 stimulated, chondrocyte mediated type II collagen breakdown from nasal cartilage.

Biological and chemical hazards of forensic skeletal analysis

In the course of conducting forensic analysis of human skeletal material, anthropologists are exposed to a number of biological and chemical hazards. This paper reviews the primary concerns in terms of infection or exposure. Handling of human tissue provides an avenue through which bloodborne pathogens may be transported. Scene recovery also includes a set of hazards through exposure to human, animal and soil vectors. Basic personnel protection and laboratory procedures should be established for the protection of all personnel involved in this work.

Bone mineral density and survival of elements and element portions in the bones of the Crow Creek massacre victims

The interpretation of archaeologically-derived skeletal series is dependent on the elements and portions of elements preserved for examination. Bone and bone portion survival is affected by factors, both intrinsic and extrinsic to the elements themselves, that influence deterioration and preservation. Among the intrinsic variables, the density of the element and element portion are particularly important with respect to the degree of preservation. Recently reported bone mineral density values from a contemporary human sample are compared to the survival of prehistoric limb bones of the Crow Creek specimens, a fourteenth-century massacre skeletal series. The contemporary density values are positively correlated with Crow Creek element and element portion survival. Two calculations of bone mineral density, however, are more closely related to preservation than a third. Such density information has implications for assessing minimum number of elements and individuals and documenting taphonomic processes.

Analysis of neurotrophin/receptor interactions with a gD-flag-modified quantitative kinase receptor activation (gD.KIRA) enzyme-linked immunosorbent assay

A rapid, sensitive, and high-capacity assay has been developed to quantify ligand-induced receptor tyrosine kinase activation in terms of receptor phosphorylation. The assay, termed a "kinase receptor activation" or KIRA-ELISA, utilizes two separate microtiter plates, one for cell culture and ligand stimulation, and the other for receptor capture and phosphotyrosine ELISA. The assay was developed for analysis of neurotrophin-induced trkA, trkB, or trkC activation. It utilizes a trkA, trkB, or trkC receptor fused with a 26-amino-acid polypeptide flag derived from HSV glycoprotein D (gD.trkA, B, or C, respectively) on the amino-terminus, stably transfected into CHO cells. Stimulated receptors were solubilized with Triton X-100 buffer and then captured in ELISA wells coated with gD-specific mAb. The degree of receptor autophosphorylation was quantified by anti-phosphotyrosine ELISA. Reproducible standard curves were generated with an EC50 of approximately 16 ng/ml NGF for gD.trkA KIRA, 11 ng/ml for NT4/5 and 20 ng/ml for BDNF in gD.trkB KIRA, and 9.4 ng/ml for NT3 in gD.trkC KIRA. When the gD.trkA KIRA assay was used to quantify serum NGF or NT3 following administration to rats, the assay agreed well with currently existing ELISA assays. When the gD.trkA KIRA assay was used to test several NGF variants, as well as NGF stability samples, the capacity of the assay to quantify ligand bioactivity compared well with the more widely used radioreceptor binding and PC 12 cell survival assays. The gD.trk KIRA assays show great potential as rapid bioassays, capable of quantitative, consistent, and stability indicating analyses.

A survey of the incidence and care of postoperative wound infections in the community

The incidence of postoperative wound infection after clean surgery in the four weeks following early discharge from hospital and its effect on community medical services have been studied prospectively. The wound infection rate as assessed by 118/155 patients who responded to a postoperative questionnaire was 9%; half of the wound problems presented after discharge. Postoperative wound infection increased the time spent by general practitioners per patient twofold, and that of practice/district nurses > or = fivefold.

Infant tufted capuchin monkeys' behaviour with novel foods: opportunism, not selectivity

To determine whether young capuchin monkeys, Cebus apellaselectively interacted with others concerning novel foods, 11 infants (4.5-12 months) living in two groups were observed following presentation of familiar or novel foods. Foods were presented either to the whole group or to infants in a section of the home cage to which only they had access. Infants showed more frequent interest in others' food and picked up foods more frequently when foods were novel, and they tended to eat novel foods more frequently than familiar foods. The pattern was the same whether the foods were presented to the group or only to infants. Infants expressed interest in others' novel foods equally often before and after sampling these foods themselves. The frequency of interest in others' food correlated positively with age. It is concluded that acceptance of novel foods in these monkeys occurs readily regardless of socially provided information about edibility. Social interactions do not appear to make important contributions to acceptance of novel foods by infant capuchin monkeys.

Prevention of urinary tract infection in patients with spinal cord injury--a microbiological review

The importance of urinary tract infection (UTI) in patients with spinal cord injury cannot be understated. Many patients with significant bacteriuria are considered to be colonised rather than infected, and treatment should be reserved for those with clinical symptoms or other signs of infection. Published research on the prevention and management of UTI in patients with spinal cord injury often has limitations due to differences in definitions of UTI, studies on groups using different urinary drainage appliances, the mixture of newly injured and longstanding injured patients and studies being carried out predominantly on male patients. The complications due to UTI and the difficulties in treating established infection mean that prevention is essential. Close urological follow-up is crucial in ensuring that adequate bladder drainage is achieved avoiding the use of long term indwelling urinary catheters if at all possible. For those patients who require long term urinary appliances patient education and strict attention to hygiene and catheter care policies is important. The role of antiseptic/ antibiotics is strictly limited in preventing UTI in patients with spinal cord injury and may even be harmful. Further study into which groups of patients may benefit from the use of antiseptics or antibiotics is urgently required. Continued research into different methods of prevention eg by vaccination, immunotherapy, the use of receptor analogues and bladder interference should also be encouraged.