Assessment of collagen film for use in urinary tract surgery

This investigation assessed a biodegradable collagen membrane which can be sutured around the ureter to prevent urine leakage, thus permitting healing to proceed more rapidly while the membrane itself is resorbed. Following an early in vitro investigation in which collagen was assessed, a more comprehensive survey has now been carried out. Tissue compatibility and biodegradation were assessed by implanting the film into the lumbar muscles of rats; it was then used to cover experimental ureterotomies in New Zealand White rabbits. The data obtained from the rabbits confirmed that a collagen membrane can prevent leakage of urine from the ureter during healing while it itself is biodegraded, indicating that a collagen membrane could be used to repair the injured urinary tract.     

Genetic origin of human anti-insulin antibodies

Numerous studies have characterized the specificity of human anti-insulin antibodies; however, little is known about their genetic origin. To initiate molecular studies, B cells that bind human insulin were selected from the peripheral blood of diabetic donors and transformed with Epstein-Barr virus. The resulting anti-insulin B-cell lines were cultured at limiting dilution and examined for immunoglobulin heavy-chain gene rearrangements on Southern gels. These studies demonstrated the clonality of the B-cell lines and showed that multiple immunoglobulin heavy chain rearrangements are present. When the heavy-chain variable region (VH) gene from one of these Epstein-Barr virus cell lines was cloned, it was found to belong to the recently identified human VHV gene family that represents less than 1% of known human VH genes. Using the polymerase chain reaction, the germline VHV gene of the donor was amplified and sequenced. The sequences showed a high level of homology (98%) between the expressed and germline VHV gene of the donor. While antibodies reactive with autologous insulin (like other autoantibodies) are not extensively mutated from their germline configuration, two replacement substitutions are present in this IgM antibody.     

Canine parainfluenza virus-induced encephalitis in ferrets

Young seronegative ferrets were intracerebrally inoculated with a neurotropic strain of canine parainfluenza (CPI) virus and serially killed at intervals after infection for subsequent viral immuno-peroxidase, light microscopical and scanning electron microscopical evaluation. The CPI virus infection resulted in a self-limiting non-suppurative ependymitis and choroiditis with associated ependymal cell degeneration. These changes were accompanied by paraventricular and perivascular cellular infiltrates of lymphocytes and monocytes, predominantly in the fourth ventricle and the cervical spinal cord and less frequently in the lateral ventricles and Sylvian duct. The inflammatory lesions were first detected on post-inoculation day (PID) 8 and had largely resolved after PID 22. Two animals showed multifocal axonal degeneration in the mesencephalon and vestibular nucleus, respectively. Immuno-histocytochemistry showed that virus replication was restricted to ependymal and subependymal cells and was most prominent on PID 4. No prominent residual lesions were present in convalescent animals. Virus-neutralizing CPI antibodies developed by PID 9 and increased slowly thereafter.     

Collagen arrangements in ureter

Summary The collagen fibres of rabbit and human ureter were exposed by digestion with trypsin and hyaluronidase. The fibre structure was examined using an SEM and examples of the inner and outer fibre structures are shown together with the effects of different types of mechanical strain. An interesting difference between the arrangements of the inner fibres of human and rabbit was seen where the human ureter had a cross-ply structure while in the rabbit it was helical.     

Influence of cerebral embolism on brain monoamines

In baboons the right cerebral hemisphere was embolised by a shower of microemboli, immediately followed by one large embolus designed to occlude the middle cerebral artery (MCA). One hour after embolism a significant, though small, reduction in blood flow and oxygen consumption of the embolised hemisphere was recorded, at which time the animals were killed and brain monoamines measured. Dopamine was reduced in the ipsilateral caudate nucleus, the reported site of maximal ischaemic damage in this model. Dopamine levels were increased in frontal and occipital grey matter sampled from areas surrounding the occluded MCA territory and in similar brain areas of the opposite non-embolised hemisphere. Noradrenaline was increased in grey matter from both cerebral hemispheres, as well as subcortical structures bilaterally. Brain 5-hydroxytryptamine levels were unaltered, but increased 5-hydroxyindoleacetic acid in cisternal cerebrospinal fluid suggested transient alteration in 5-hydroxytryptamine metabolism after embolism. The effects of cerebral embolism on brain monoamine metabolism appear to be different from the effects of permanent surgical occlusion of major cerebral vessels. The bilaterality of effects after unilateral hemispheric embolism might be related to diaschisis. The mechanisms of the observed changes, as well as their relevance to the progression of cerebral ischaemia and the complications associated with cerebral embolism, still require to be established.