Evolution of tropical land temperature across the last glacial termination.

The tropical West Pacific hosts the warmest part of the surface ocean and has a considerable impact on the global climate system. Reconstructions of past temperature in this region can elucidate climate connections between the tropics and poles and the sensitivity of tropical temperature to greenhouse forcing. However, existing data are equivocal and reliable information from terrestrial archives is particularly sparse. Here we constrain the magnitude and timing of land temperature change in the tropical West Pacific across the last deglaciation using an exceptionally precise paleothermometer applied to a well-dated stalagmite from Northern Borneo. We show that the cave temperature increased by 4.4 ± 0.3 °C (2 SEM) from the Last Glacial Maximum to the Holocene, amounting to 3.6 ± 0.3 °C (2 SEM) when correcting for sea-level induced cave altitude change. The warming closely follows atmospheric CO2 and Southern Hemisphere warming. This contrasts with hydroclimate, as reflected by drip water δ18O, which responds to Northern Hemisphere cooling events in the form of prominent drying, while temperature was rising. Our results thus show a close response of tropical temperature to greenhouse forcing, independent of shifts in the tropical circulation patterns.

Synthetic peptides which inhibit the interaction between C1q and immunoglobulin and prolong xenograft survival.

BACKGROUND: Acute vascular xenograft rejection (AVXR), also termed delayed xenograft rejection (DXR), occurs when hyperacute rejection (HAR) is prevented by strategies directed at xenoreactive natural antibodies and/or complement activation. We have hypothesized that AVXR/DXR is initiated in part by early components of the complement cascade, notably C1q. We have developed synthetic peptides (termed CBP2 and WY) that interfere with the interaction between C1q and antibody. METHODS: CBP2 and the WY-conjugates were used as inhibitors of immunoglobulin aggregate binding to solid phase C1q. Inhibition of complement activation by the peptides of the classical system was determined using lysis assays with sensitized sheep red blood cells or porcine aortic endothelial cells as targets and of the alternate complement pathway using guinea pig red blood cells as targets. Two transplant models were used to study the effects of administering peptides to recipients: rat heart transplant to presensitized mouse, and guinea heart transplant to PVG C6-deficient rats. RESULTS: CBP2 and WY-conjugates inhibited immunoglobulin aggregate binding to C1q. The peptides also inhibited human complement-mediated lysis of sensitized sheep red blood cells and porcine aortic endothelial cells in a dose-dependent manner and the WY-conjugates prevented activation of the alternate complement pathway as shown by inhibition of guinea pig red blood cells lysis with human serum. In addition, the use of the peptides and conjugates resulted in significant prolongation of xenograft survival. CONCLUSIONS: The CBP2 and WY peptides exhibit the functional activity of inhibition of complement activation. These peptides also prolong xenograft survival and thus provide reagents for the study of the importance of C1q and other complement components in transplant rejection mechanisms.

Expression and immune response to islet antigens following treatment with low doses of streptozotocin in H-2d mice.

Insulin dependent diabetes mellitus (IDDM) is likely to be due to the immunologic destruction of the islets of Langerhans. However, the relative importance of expression of a unique set of islet antigens or of differences in immune responses to those antigens in determining susceptibility to auto-immune diabetes is unknown. To a large extent, the reason for this uncertainty is the difficulty in directly identifying islet antigens expressed in vivo. We have studied the relationship between islet antigen expression, immune responsiveness to islet antigens, and the development of diabetes in diabetes induced by multiple low-doses of streptozotocin (STZ) in mice of the H-2d haplotype. We identified the expression of relevant islet antigens by testing the ability of STZ treated islets to induce tolerance to diabetes in C57BL/KsJ mice after intrathymic transplantation. C57BL/KsJ but not BALB/cByJ mice developed hyperglycaemia and insulitis following STZ treatment. Interferon-gamma transcription was detected in intrapancreatic lymphocytes from C57BL/KsJ mice but at lower levels in cell from BALB/cByJ. IL-4 levels were higher in BALB/cByJ than C57BL/KsJ. Intrathymic STZ-treated islets from syngeneic mice induced tolerance to diabetes in C57BL/KsJ mice following transient depletion of mature peripheral T cells, but islets from resistant BALB/cByJ mice did not induce tolerance to disease in C57BL/KsJ mice even though they did cause tolerance to the alloantigens. (C57BL/KsJ x BALB/cByJ)F1 mice developed hyperglycaemia like the susceptible parent following STZ treatment, and islets from these mice induced tolerance to MDSDM when treated with STZ and transplanted intrathymically into C57BL/KsJ. We conclude the expression of islet antigens and the intrapancreatic responses to STZ treated islets differs between mice that are susceptible and resistant to multi-dose streptozotocin induced diabetes mellitus.

Early histopathology of small intestinal discordant xenografts.

A descriptive study of a new model enabling serial biopsies of ongoing hyperacute rejection of small intestinal discordant xenografts is presented. In a series of guinea-pig-to-Lewis rat small bowel xenotransplants (n=7), aboral free ends of Thierry-Vella loops constructed from the graft were sequentially biopsied at one-minute intervals up to ten minutes post-reperfusion and less frequently thereafter. In a guinea pig-to-guinea pig (n=6) isograft series, biopsy controls for preservation/ischemia-reperfusion injury were obtained. Xenoantibody sequestration in this model was evaluated in a separate series of transplants, utilizing an ELISA assay for rat anti-guinea pig natural antibodies. Pathologic evaluation revealed a unique series of events characterized with microcirculatory failure and thrombosis progressing from the submucosal vasculature to the lumen. Within the system's detection limits, complement deposition and P-selectin expression occurred as early as one minute post-reperfusion, preceding the staining for IgM and IgG. Using rat serum ELISAs, no significant difference in xenoantibody sequestration was detected between the xenograft and isograft groups. The guinea pig-to-rat discordant small bowel xenotransplantation is an efficient small animal model to dissect the very early pathophysiologic events during hyperacute rejection.

Intrathymic transplantation of islet antigen affects CD8+ diabetogenic T-cells resulting in tolerance to autoimmune IDDM.

The acquisition of T-cell tolerance in the thymus is limited to those antigens expressed in the thymus at the time of T-cell development. Normally, islet antigens that are involved in insulin-dependent diabetes mellitus (IDDM) are not present in the thymus, but we have previously shown that transplantation of islets expressing relevant antigens into the thymus at the time of T-cell maturation results in prevention of IDDM in the multidose streptozotocin model of diabetes mellitus (MDSDM). Although both CD4+ and CD8+ T-cells are involved in the pathogenesis of this disease, the cells affected by intrathymic transplantation of islets are unknown. In this study, we have identified which T-cell subsets are affected by intrathymic islet antigens. Streptozotocin (STZ)-treated syngeneic islets were transplanted into the thymuses of C57BL/KsJ mice, and CD4+, CD8+, or both subsets of cells were transiently depleted with monoclonal antibodies (mAbs). After T-cell repopulation, animals that had received intrathymic islets followed by anti-CD8 mAb (P < 0.05) or both anti-CD4 and anti-CD8 mAbs (P < 0.01) but not anti-CD4 mAb alone were resistant to the development of autoimmune diabetes after five low doses of STZ. Insulitis was also reduced in mice receiving intrathymic islets and anti-CD8 (P < 0.025) or both anti-CD4 and anti-CD8 mAbs (P < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Monsanto's computer animal proposal system (CAPS).

Regulations and standards must include the minimum requirements with respect to veterinary care, sanitation, handling, feeding, and housing. Part 1 of the Animal Welfare Act regulations was amended to update, clarify, and expand the list of definitions of terms and standards. Section 9 CFR, Part 1, contains definitions and deals with animal welfare, animal housing, dealers, exhibitors, research facilities, and humane animal handling. The subjects in 9 CFR, Part 2, pertain to licensing, registration, identification of animals, records, institutional animal care and use committees, and adequate veterinary care. Animal welfare, humane animal handling, pets, transportation, and reporting and recordkeeping requirements are the subjects listed in 9 CFR, Part 3.

Induction of tolerance to autoimmune diabetes with islet antigens.

The development of T cell tolerance to self-antigens is imparted principally through negative selection events during thymic ontogeny. However, this tolerance may be limited to antigens that are expressed in the thymus, and additional mechanisms are probably required to regulate autoimmune responses to tissue-specific antigens. Autoimmune diabetes can be induced experimentally by treating susceptible stains of mice with multiple low doses of streptozotocin (STZ). In this report we show that transplantation of isolated islets of Langerhans into the thymuses of adult C57BL/KsJ mice will induce tolerance to the subsequent induction of autoimmune diabetes. This tolerance is tissue specific and thymus dependent. It was not induced by thymic transfer of adrenal tissue or by kidney transfer of islets. Furthermore, depletion of mature T cells was required and the tolerant state was abrogated by the adoptive transfer of normal splenocytes. It is interesting that pretreatment of the islets with STZ enhanced their ability to induce tolerance, and suggests that antigen shedding induced by tissue damage may facilitate transfer of islet antigens to tolerizing cells in the thymus. These findings indicate that thymic tolerance specific for tissue can be stimulated to occur in the presence of atopic tissue-specific intrathymic antigens. Elimination of disease-related T cells in the absence of global immunosuppression represents a novel approach for the prevention of autoimmune disease.

Stress conditioning: a novel approach to organ preservation.

Effective stress conditioning can extend the safe cold storage time of rat kidneys to 48 hours. We demonstrated that planned induction of the stress response, by heat shock, can be used to stress condition the transplant organ and protect it against the damages of cold storage. A powerful and useful protective mechanism exists in a latent form in all cells. This mechanism can be rapidly activated in a controlled and planned way to allow tissues temporarily to resist injury. Through stress conditioning it is possible to provide a high level of protection in situations in which stress can be anticipated and planned for.

Surgery: a radical approach to severe hydrofluoric acid burns. A case report.

Generally, chemical burns of the skin, both acid and caustic, are best treated initially by irrigating with copious amounts of water. Subsequently the burn is managed as one would treat a thermal burn. An exception may exist when skin burn is caused by hydrofluoric acid (HF), especially in its anhydrous form. HF is a commonly used catalyst in the petrochemical industry. The following report concerns a life-threatening burn from anhydrous HF.

Effectiveness of employee training and motivation programs in reducing exposure to inorganic lead and lead alkyls.

The Occupational Safety and Health Administration has advanced engineering controls over administrative controls and protective equipment to reduce exposures to chemicals in the workplace. The application of employee training and motivation programs (such as job safety analysis) to reduce exposures to chemicals has not been emphasized. To determine the effectiveness of such programs, a pilot project in an alkyl lead production facility was conducted with 35 employees in an effort to reduce exposures to organic and inorganic lead. Results after 12 months show a 40% reduction in lead-in-urine and a 24% reduction in lead-in-blood, both indicators of total exposure to organic inorganic lead.