In vitro dedifferentiation of fetal porcine pancreatic tissue prior to transplantation as islet-like cell clusters

The fetal porcine pancreas under experimental conditions can be transplanted in the form of explants or islet-like cell clusters (ICCs) to normalize blood glucose levels in diabetic recipients. ICCs are released from the collagenase-digested pancreas and require a 4- to 5-day culture period for their complete formation. In order to maximize insulin producing beta cell differentiation following transplantation, an understanding of ICC development is essential to utilize this alternative treatment for type 1 diabetes. In this study a role is proposed for exocrine cells in the generation of the multipotent pancreatic precursor cells during the culture period. Acinar cells undergo dedifferentiation during the initial stages of the culture period into multipotent pancreatic precursor cells, previously called protodifferentiated cells. The progressive loss of exocrine differentiation appears to involve rapid degranulation of zymogen granules by exocytosis and loss of the prominent secretory apparatus. These processes occur in parallel with a significant reduction in the expression of lipase in the period from day 0 to day 5 and simultaneously there is an increase in the epithelioid/ductal cell marker, cytokeratin 20. Using proliferating cell nuclear antigen, cell proliferation during the culture period does not appear to account for the increase in epithelioid/ductal cells. Further the rates of apoptosis and necrosis which were identified using the TUNEL technique and propidium iodide, respectively, do not appear to account for the reduction in exocrine cell numbers. Exocrine cell dedifferentiation appears to increase the pool of protodifferentiated cells which have the potential to develop into the insulin-producing beta-cell population following transplantation into the diabetic recipient     

Hepatitis E virus infection in chimpanzees: a retrospective analysis

Summary.  Different patterns of disease were observed among 11 chimpanzees who were inoculated intravenously with hepatitis E virus (HEV) positive fecal specimens from four different outbreaks (Nepal 1981, Uzbekistan 1981, Pakistan 1985, and Mexico 1986). Five chimpanzees had marginal or no liver enzyme elevations within 70 days of inoculation. Two of the chimpanzees had limited viremia, but did not produce detectable antibody. The four remaining chimpanzees had liver enzyme elevations, viral shedding, viremia, seroconversion to anti-HEV, and detectable HEV antigen in liver biopsy specimens. These results may reflect the range of infection patterns that develop in humans after natural exposure to the HEV. Received December 29, 1999/Accepted February 21, 2000     

Pre-term birth and severe pre-eclampsia are not associated with altered expression of HLA on human trophoblasts

PROBLEM: The unusual pattern of human leukocyte antigen (HLA) expression on human trophoblasts could play an important role in successful pregnancy outcome. To determine whether alterations in HLA expression are associated with pregnancy abnormalities we have investigated expression of these antigens on chorionic and extravillous cytotrophoblasts. METHODS: Frozen tissue sections of placenta and fetal membranes were collected after pre-term spontaneous delivery, severe pre-eclampsia pre-term Caesarean section, normal term delivery and term Caesarean section. HLA expression was analyzed by immunohistochemistry. RESULTS: We did not observe differences in the expression of HLA on chorionic and extravillous cytotrophoblasts in pregnancy abnormalities. However, we noted higher expression levels of HLA class Ia molecules in amnion epithelial cells in pre-term deliveries. Furthermore, in severe pre-eclampsia the number of extravillous cytotrophoblast islands were elevated when compared with pre-term deliveries. CONCLUSIONS: No alterations in expression of HLA class Ia, HLA-G and HLA class II on human trophoblasts in pregnancy abnormalities were seen.     

Microvascular function in skin windows.

The dermal microvasculature is an integral component of skin windows. However, in spite of the obvious dependence of the skin window model on vascular function, its almost exclusive application has been the study of leukocyte function and recovery of the cellular components of inflammatory exudates. In the studies reported here, skin window chambers were employed for assessment of function of the underlying microvasculature in rats given intravenous infusions of Evans blue dye or colloidal carbon. Increased vascular permeability was documented by photometric measurement of Evans blue dye, and vascular labeling of dermal vessels with colloidal carbon was assessed histologically. Zymosan-activated serum elicited accumulation of both leukocytes and Evans blue dye in chamber fluid overlying skin windows, confirming the responsiveness of the preparations. With serotonin as a model vasoactive substance, both increased vascular permeability and vascular labeling were directly related to serotonin concentration in the chamber fluid. It is estimated that plasma exudates were distributed as approximately 10% in the fluid and 90% in the dermis. Finally, serotonin-induced exudates recovered from the 0.3-ml chambers were estimated to be up to 3 microliter of plasma based on Evans blue dye measurement or up to 70 micrograms of protein based on Lowry assay. Thus, soluble components of skin window exudates were recovered for examination, and the dermal microvasculature was shown to be an important functional component of the skin window model that was directly accessible for study.     

Immunological Unresponsiveness in Guinea Pigs: II. The Effect of Unresponsiveness on the Development of Delayed Type Hypersensitivity to Protein Antigens

Guinea pigs were rendered incapable of making circulating antibody against bovine serum albumin (BSA) or human gamma globulin (HGG), by prenatal and/or neonatal contact with these antigens. They were then treated with a water in oil emulsion of picryl BSA, or with HGG in Freund's adjuvant, or with HGG precipitated with excess rabbit antibody and suspended in a water in oil emulsion, such as to produce a state of delayed hypersensitivity to BSA or HGG respectively in control animals. The guinea pigs which would not make antibody failed to become hypersensitive to these antigens. In one group of unresponsive animals treatment with HGG in Freund's adjuvant resulted in antibody production, but no phase of delayed hypersensitivity was observed.     

Morphology and axonal projection patterns of individual neurons in the cat perigeniculate nucleus

1. The lateral geniculate nucleus is the primary thalamic relay through which retinal signals pass en route to cortex. This relay is gated and can be suppressed by activity among local inhibitory neurons that use gamma-aminobutyric acid (GABA) as a neurotransmitter. In the cat, a major source of this GABAergic inhibition seems to arise from cells of the perigeniculate nucleus, which lies just dorsal to the A-laminae of the lateral geniculate nucleus. However, the morphological characteristics of perigeniculate cells, and particularly the projection patterns of their axons, have never been fully characterized. We thus examined the morphology of these cells: individually by intracellular injection of horseradish peroxidase (HRP) and en masse with the anterograde tracer Phaseolus vulgaris leucoagglutinin (PHAL). 2. We recorded from 12 perigeniculate cells that we impaled and successfully labeled with HRP. These cells exhibited response properties generally consistent with those described previously. They had long response latencies to stimulation of the optic chiasm and relatively large, often diffuse, receptive fields. The visually evoked responses of most of the cells were dominated by one eye. Compared with cells of the lateral geniculate nucleus, perigeniculate cells had large somata (517 +/- 136 microns 2 in cross-sectional area, mean +/- SD), which were fusiform or multipolar in shape, and dendritic arbors that extended a considerable distance (1,095 +/- 167 microns) parallel to the border between the perigeniculate and lateral geniculate nuclei. Terminal arbors of some dendrites were quite complex and beaded. 3. The axons of six perigeniculate cells were labeled sufficiently well to trace and reconstruct over a considerable distance. Each of these axons formed branches that descended to innervate the lateral geniculate nucleus, and this geniculate innervation was exclusively limited to the A-laminae. Terminal boutons within the A-laminae were nearly all en passant, which gave the axons a beaded appearance. Furthermore, branches of five of these six axons provided local innervation of the perigeniculate nucleus, generally within each labeled cell's own dendritic arbor. Three of the cells also exhibited an axon branch that extended medially and caudally away from the soma, but we were unable to trace these axon branches to their targets. 4. Within the lateral geniculate nucleus, each arbor of perigeniculate axons derived from two main components. One was a narrow, sparse medial component that innervated laminae A and A1.(ABSTRACT TRUNCATED AT 400 WORDS)     

Antibodies with Differing Molecular Sizes in Mice

The antibody responses of C₃H mice to haemocyanin, pneumococcal polysaccharide (SSS III) and sheep erythrocytes were studied after a single intravenous administration. Serum antibody against each antigen was present on the fifth, but not on the third day.

Antibodies against haemocyanin and against SSS III migrated electrophoretically as γ globulins and had the ultracentrifugal sedimentation properties of 6.5S globulins. Sheep erythrocyte haemolysins were largely γ macroglobulins which sedimented in the ultracentrifuge in the manner of 18S globulins. A small proportion of haemolysin activity was found among the 6.5S γ globulins.

     

Preoperative radiation and surgery for cancer of the rectum. Veterans Administration Surgical Oncology Group Trial II

In a prospective randomized trial, 361 male patients with histologically proven adenocarcinoma of the rectum, judged preoperatively to require abdominoperineal resection (APR), were treated by surgery alone or were given 3,150 rads of preoperative radiotherapy. Surgical resection was done on 320 patients, 262 having "curative" APR. Only moderate symptoms from radiotherapy were noted and postoperative complications and 30-day mortality were similar in both groups. Five-year survival for curative APR was the same in both groups (50% for both treated and control patients). The incidence of positive lymph nodes in the resected specimens was 35% in treated and 41% in controls. In the first preoperative radiotherapy trial conducted by the group, 5-year survival in patients undergoing "curative" APR was 47% in treated versus 34% in control groups. Additionally, the difference in positive lymph nodes in the resected specimens was substantially greater in the first trial (26% in treated versus 44% in controls).     

Chronic lymphocytic leukemia and acquired disorders affecting the immune system: a case-control study

The relationship of a number of subacute or chronic infectious diseases, connective tissue or autoimmune disorders, allergic conditions, and surgical excision of lymphoid tissue with chronic lymphocytic leukemia (CLL) was examined in a case-control study involving 342 cases and 342 matched controls. In both analyses of all matched pairs and those pairs in which both subjects were respondents, no statistically significant association was found between a history of subacute viral infections or subacute and chronic bacterial infections and CLL. Connective tissue or autoimmune disorders also were found not to be associated with CLL. Examination of the association between several allergic conditions and CLL suggested a protective effect as did a "dose-response" analysis, although none of the individual disorders showed a statistically significant relationship; however, a test for linear trend was significant (P = .04). Similarly, examination of the relationship between surgical excision of lymphoid tissue in several anatomic locations and CLL showed a protective effect, statistically significant for tonsillectomy-adenoidectomy (odds ratio = 0.69; 95% confidence interval = 0.48, 0.98). A statistically significant negative dose-response relationship, substantiating the protectiveness of the effect, was found.     

Sizes, laminar and topographic origins of cortical projections to the major divisions of the red nucleus in the monkey

The retrograde transport of horseradish peroxidase was used to study the topographic and laminar origins of the cortical projections to the parvocellular and the magnocellular divisions of the red nucleus in Macaca mulatta and Macaca fascicularis. Approximately 90% of the corticorubral projection is directed to the parvocellular division of the nucleus. Corticoparvocellular (CRp) neurons are pyramidally shaped, are smaller in size than corticospinal neurons, and are more numerous. They are found principally in sublamina Va of cytoarchitectonic areas 4 and 6, and in moderate quantities in sublamina Vb of posterior area 8 and area 5. In areas 4 and 6, the cells are grouped in clusters of three to 15 neurons each and are arranged in cellular bands of varying rostrocaudal thickness which course mediolaterally. With respect to functionally defined zones, CRp neurons are found throughout the supplementary motor area and the precentral motor cortex. In addition, they are found in parts of areas 5, 6, and 24 that project to these cortical motor areas, and that are thought to have "premotor" or movement-programming functions. The corticomagnocellular (CRm) projection arises principally from cells in sublamina Vb of the precentral arm and leg areas (area 4), and from adjacent parts of posterior area 6, CRm cells are pyramidally shaped, and their size distribution is bimodal, with peaks that correspond, respectively, to the modal diameters of CRp and of corticospinal neurons. These results and those of previous studies suggest that CRm neurons are involved principally in the control of hand and foot movements, with little effect on more proximal musculature. The massive CRp projection, however, is clearly part of a large cerebrocerebellar communication system, with motor and/or movement programming functions that have yet to be clearly defined.