Monoclonal antibodies specific for the bundle-forming pilus of enteropathogenic Escherichia coli.

The bundle-forming pilus (BFP) produced by enteropathogenic Escherichia coli (EPEC) is associated with the presence of a large EPEC adherence factor plasmid and the formation of localized adherence clusters on tissue culture cells. Three mouse monoclonal antibodies (ICA2, ICA3, and ICA4) were produced against BFP purified from EPEC B171 (O111:NM). These monoclonal antibodies reacted in immunoblots with different epitopes of the 19.5-kDa bundlin subunit of BFP of heterologous EPEC. These reagents could serve as diagnostic tools for the identification of EPEC as well as for studying the role of BfpA in the interaction of EPEC with eukaryotic cells.     

Effect of treatment with octreotide on the morphology of growth hormone—secreting pituitary adenomas: Study of 24 cases

Twenty-four acromegalic patients were treated with octreotide subcutaneously for periods of 3 to 6 weeks (group I, 12 cases) or 6 months (group II, 12 cases) before transsphenoidal surgery. Radiological studies performed in 19 patients before and at the end of this treatment period revealed no changes in 8 cases. In 8 other cases, a slight reduction in tumorsize was observed, and in 3 cases an important shrinkage was documented. At surgery, the adenomatous tissue appeared softer than in nonpretreated patients, facilitating the operation. Pathological examination revealed widening of perivascular spaces with accumulation of fibrous tissue and more crinophagy than in nonpretreated patients but failed to reveal morphologically pronounced cell involution as observed in prolactin-producing adenomas treated with dopamine agonists. No significant difference in frequency or extent of cellular changes was noted between the two groups. These morphological findings seem to be more consistent with a functional inhibition of growth hormone release than with cellular alterations induced by octreotide.     

The effects of hip contact aberrations on stress patterns within the human femoral head

A two-dimensional finite element model incorporating cancellous bone inhomogeneity is used to study femoral head stress alterations caused by changes from the usual articular contact patterns. The contact stress distributions, calculated from an earlier mathematical analysis by Greenwald and O'Connor (16), are found to influence not only the adjacent subchondral bone, but relatively distant parts of the head as well. Both abnormally large joint incongruity and abnormally low cartilage compliance cause load to shift away from the superior “weight-bearing” area, out toward the periphery of the contact region. As a consequence, transverse compressive stresses, which are of appreciable magnitude but which do not contribute to weight bearing, are built up throughout much of the superior and central portions of the femoral head. Most small changes in the overall cartilage thickness or in its thickness distribution, when considered in isolation from hip compliance changes, have only minor effects on the internal stress distribution. An important exception is cartilage thinning at the superior margin, which can result in abrupt longitudinal compressive stress concentrations. It is suggested that such alterations of the normal patterns of stress transmission may contribute to sclerosis or to the formation of osteophytes or cysts in the osteoarthritic hip. This study was aided by grants from the Easter Seal Research Foundation (#N7739), the National Science Foundation (#ENG78-05451), the Barra Foundation, Inc., and the Western Pennsylvania Chapter of the Arthritis Foundation. The authors wish to acknowledge the excellent service provided by the University of Pittsburgh Computer Center. The assistance of Mr. Gary E. Graf and Mrs. Diana W. Montgomery are also appreciated.     

Chronic intracranial pressure monitoring by telemetry: Clinical experience

Intracranial pressure (ICP) monitoring is a critical measure for avoiding severe brain dysfunction or brain death by directing supportive therapy so as to prevent ICP increase severe enough to reduce cerebral blood perfusion. Such situations occur with brain swelling, increased cerebral vascular volume, and increase in cerebrospinal fluid (CSF) volume. Causes include ischemic stroke, subarachnoid bleeding, brain contusion, encephalitis (as in Reye's syndrome), and hydrocephalus from meningitis or neoplasm. When several days of ICP monitoring can direct resolution of the pressure crisis, the invasive direct connection of an intracranial sensor with external recording device carries only minimal infection risk. Prolonged ICP monitoring for weeks or months demands telemetry and becomes desirable in a number of chronic disease problems including both congenital and acquired hydrocephalus where enlarged and pressurized cerebral ventricles develop with reduced absorption of continuously secreted CSF. Although the primary disturbance in CSF circulation can remain incurable, its palliation by valve-regulated CSF diversions or shunting can restore normal brain function and in infants permit normal brain development. Missing this goal can result from failure to maintain a sufficiently normal pattern of CSF dynamics and ICP. Monitoring of the CSF pressure fluctuations transmitted through an intraventricular catheter provides the most accurate record of ICP pulsations. Therefore, a pressure sensing module can be “T'd” into an existing shunt system in continuity with the already placed ventricular tube. The capacity to monitor ICP accurately by telemetry was first established in dogs made hydrocephalic to assure free CSF pulse through a ventricular catheter (1,2,3, 4,5). The subsequent use of ICP monitoring by telemetry in three patients will be described.     

Simultaneous measurements of temperature and pH in vivo using NMR in conjunction with TmDOTP5-

NMR techniques for temperature and pH measurements have attracted increasing interest in recent years, motivated in part by the growing importance of medical hyperthermia for the treatment of cancer. The chemical shifts of thulium 1, 4, 7, 10-tetraazacyclododecane-1, 4, 7, 10-tetrakis(methylene phosphonate) (TmDOTP5-) have been studied as a function of temperature and pH. The results demonstrate that TmDOTP5- resonance shifts are highly sensitive to temperature (approximately 1.0 ppm/degrees C) and pH (approximately 3.2 ppm/pH unit) at clinically relevant field strengths. A new method is presented which utilizes two magnetically non-equivalent protons in TmDOTP5- for simultaneous NMR measurements of both temperature and pH. The difference in the chemical shift values of pairs of 1H resonances provides a temperature sensitivity of about 1.6 ppm/ degrees C. The technique is demonstrated in live rats undergoing ultrasound-induced hyperthermia therapy.     

Special behavioral paradigms in animals to study age-related changes in memory

Animal models are important to understand age-related changes in humans. However, the models do not always agree about the effects of aging on memory, and some of the results with animals are different from those with humans. Points of similarity and difference are discussed, indicating some directions for future research.     

Acute hepatitis B virus infection by genotype F despite successful vaccination in an immune-competent German patient.

BACKGROUND: Hepatitis B Virus (HBV) infection is a leading cause of chronic hepatitis and liver cirrhosis worldwide, and efficient protection can usually be achieved by vaccination that is based on recombinant HBsAg protein from HBV genotype A and D. RESULTS: Here we report the case of a fully immune-competent German patient that acquired a symptomatic acute HBV infection during adulthood despite a complete and formally successful vaccination, which had resulted in anti-HBs titers considered protective. Further phylogentic analysis identified an infection with the rare genotype F of HBV, possibly acquired in Spain, without apparent aberrations in the immunodominant 'a' determinant domain of the envelope gene. However, sequence comparisons revealed that all reported genotype F isolates display marked differences from the other genotypes in this domain which serves as an epitope for humoral immune responses. CONCLUSIONS: The rare HBV genotype F, as detected in this immune-competent, previously vaccinated patient, has marked sequences differences in the envelope/polymerase gene. Therefore, current HBV vaccines based on genotype A and D may not result in full protective immunity towards viral strains from genotype F.     

The mutational spectrum of brachydactyly type C

Growth/differentiation factor-5 (GDF5), also known as cartilage-derived morphogenetic protein-1 (CDMP-1), is a secreted signaling molecule that participates in skeletal morphogenesis. Heterozygous mutations in GDF5, which maps to human chromosome 20, occur in individuals with autosomal dominant brachydactyly type C (BDC). Here we show that BDC is locus homogeneous by reporting a GDF5 frameshift mutation segregating with the phenotype in a family whose trait was initially thought to map to human chromosome 12. We also describe heterozygous mutations in nine additional probands/families with BDC and show nonpenetrance in a mutation carrier. Finally, we show that mutant GDF5 polypeptides containing missense mutations in their active domains do not efficiently form disulfide-linked dimers when expressed in vitro. These data support the hypothesis that BDC results from functional haploinsufficiency for GDF5.