Acute brief heat stress in late gestation alters neonatal calf innate immune functions.

Heat stress, as one of the environmental stressors affecting the dairy industry, compromises the cow milk production, immune function, and reproductive system. However, few studies have looked at how prenatal heat stress (HS) affects the offspring. The objective of this study was to evaluate the effect of HS during late gestation on calf immunity. Calves were born to cows exposed to evaporative cooling (CT) or HS (cyclic 23-35°C) for 1 wk at 3 wk before calving. Both bull and heifer calves (CT, n=10; HS, n=10) were housed in similar environmental temperatures after birth. Both CT and HS calves received 3.78 L of pooled colostrum within 12 h after birth and were fed the same diet throughout the study. In addition to tumor necrosis factor α, IL-1ß, IL-1 receptor antagonist (IL-1RA), and toll-like receptor (TLR)2, and TLR4 mRNA expression, the expression of CD14(+) and CD18(+) cells, and DEC205(+) dendritic cells were determined in whole blood samples at d 0, 3, 7, 14, 21, and 28. The neutrophil to lymphocyte ratio, differential cell counts, and the hematocrit were also determined. During late gestation, the HS cows had greater respiration rates, rectal temperatures, and tended to spend more time standing compared with the CT cows. The HS calves had less expression of tumor necrosis factor-α and TLR2 and greater levels of IL-1ß, IL-1RA, and TLR4 compared with CT calves. The HS calves also had a greater percentage of CD18(+) cells compared with the CT calves. Additionally, a greater percentage of neutrophils and lesser percentage of lymphocytes were in the HS calves compared with the CT calves. The results indicate that biomarkers of calves' immunity are affected in the first several weeks after birth by HS in the dam during late gestation.

A secretin i.v. infusion activates gene expression in the central amygdala of rats.

For the last 100 years secretin has been extensively studied for its hormonal effects on digestion. Recent observations that the deficits in social reciprocity skills seen in young (3-4-year-old) autistic children are improved after secretin infusions suggest an additional influence on neuronal activity. We show here that i.v. administration of secretin in rats induces Fos protein expression in the neurons of the central amygdala as well as the area postrema, bed nucleus of the stria terminalis, external lateral parabrachial nucleus and supraoptic nucleus. However, secretin infusion did not induce Fos expression in the solitary tract nucleus or paraventricular nucleus, regions normally activated by related peptides such as cholecystokinin. The peak blood levels of secretin that induce Fos protein expression in rat brain are similar to the peak blood levels observed during i.v. treatment with secretin in humans. The amygdala is known to be critical for developing reciprocal social interaction skills and abnormalities in this brain region have been demonstrated in autistic children.

Immunodetection approaches and high-performance immunoaffinity chromatography for an analogue of bovine growth hormone releasing factor at trace levels.

An indirect detection method using high-performance immunoaffinity chromatography (HPIAC) was used to measure low levels of an analogue of bovine Growth Hormone Releasing Factor (bGHRF). An antibody (Ab) labelled with alkaline phosphate (ALP) was incubated with the bGHRF analogue to perform a complex between the antigen (Ag) and the antibody-enzyme (Ab-En) conjugate. The complex was then injected onto a cartridge containing an immobilized Ag affinity support. Species which were not recognized by the affinity cartridge, i.e. eluted, were then directly combined, via a connecting tee, with a buffer containing a substrate. Incubation proceeded on-line, inside a knitted reactor coil, under conditions of constant flow. The subsequent generation of a fluorescently active substrate product was detected by conventional means. The assay described has a linear response region from 1.0 to 25 ng of the bGHRF analogue and a limit of detection of 0.60 ng (1.7 x 10(2) femtomole, 30 p.p.b.). This approach was compared against a method in the antigen/Ab-En complex was injected onto a immobilized Ab affinity cartridge to form an antibody-antigen conjugate sandwich and subsequent stop-flow incubation with substrate.

Temporal relation of calcium-calmodulin binding and neuronal damage after global ischemia in rats.

BACKGROUND AND PURPOSE: This study explores the temporal relation of the severity of ischemia and calcium-calmodulin binding in vulnerable and resistant brain regions in a commonly used model of global ischemia. METHODS: Immunohistochemical assay of free calmodulin unbound to calcium and light microscopic histological damage were measured in rats after 5, 10, or 20 minutes of global ischemia. RESULTS: After 24 hours of reperfusion, decreased calmodulin staining, representing increased calcium influx and calcium-calmodulin binding, correlated with increasing durations of ischemia across all brain regions. Based on a 4-point scale (4, extensive stain; 0, no staining), calmodulin staining after 5 minutes versus 10 minutes of ischemia was 3.2 versus 1.9, respectively (p less than 0.05) and after 10 minutes versus 20 minutes of ischemia was 1.9 versus 1.0, respectively (p less than 0.01). The CA1 region displayed the greatest sensitivity to ischemia. Similar but less dramatic results were seen after 2 hours of reperfusion. After 72 hours of reperfusion, histological damage closely correlated with calcium-calmodulin binding after variable durations of ischemia. A threshold of 10 minutes of ischemia was required to cause calcium-calmodulin binding and irreversible neuronal damage. Surviving neuronal populations showed recovery of calmodulin staining 7 days after ischemia, representing a return of free calmodulin and normal calcium homeostasis. CONCLUSIONS: These correlations between calcium-calmodulin binding, histological damage, and duration of ischemia support the causal role of calcium influx in global ischemic injury and suggest the need for very rapid intervention after ischemia if calcium-mediated damage is to be prevented.

A perceptual study of the role of the president of the medical staff.

This study examines how medical staff presidents and hospital administrators perceive the president's role. The perceived role of the president is compared to hospital typology as measured by hospital size, technology, and form of ownership. Overall, there is little difference between how hospital administrators and presidents view the president's role. There is substantial agreement on steps that should be taken to increase the effectiveness of the president. A widespread view is that the president should receive formal management training and be an active member of the hospital's board of trustees.

Neuronal protection correlates with prevention of calcium-calmodulin binding in rats.

We correlated the efficacy of several clinically relevant pharmacotherapies with their ability to prevent calcium influx into neurons and subsequent binding to calmodulin. We studied the administration of CGS 19755, nimodipine, nicardipine, and combinations of these drugs before or immediately after ischemia in globally ischemic rats. Calcium-calmodulin binding was graded by an immunohistochemical assay after 2 and 24 hours of reperfusion (n = 5-6 at each time period), and histologic damage was graded by light microscopy after 72 hours of reperfusion (n = 6). Calcium-calmodulin binding correlated with the severity of delayed histologic damage in various brain regions. In untreated ischemic control rats, marked calcium-calmodulin binding was seen in CA1 and CA3 after 24 hours of reperfusion (p less than or equal to 0.01). Administered before ischemia, CGS 19755 prevented calcium-calmodulin binding across all brain regions after 2 and 24 hours of reperfusion compared with controls (p less than or equal to 0.05). This effect was most prominent in CA3 and CA1, where the drug also reduced delayed neuronal damage (p less than or equal to 0.05). Lower doses or postischemic administration of CGS 19755, nimodipine, nicardipine, and a combination of postischemic CGS 19755 and nicardipine had a more limited effect on calcium-calmodulin binding and did not protect against delayed neuronal damage.(ABSTRACT TRUNCATED AT 250 WORDS)

CGS-19755, a competitive NMDA receptor antagonist, reduces calcium-calmodulin binding and improves outcome after global cerebral ischemia.

We evaluated several doses of cis-4-(phosphonomethyl)-2-piperidine-carboxylic acid (CGS-19755), a potent competitive N-methyl-D-aspartate (NMDA) receptor antagonist, systemically administered either before or after 20 to 30 minutes of global ischemia in rats. We measured outcome by mortality, histological damage by light microscopy, and learning ability on an eight-arm maze, and determined the drug's mechanism of action by an immunohistochemical assay of calcium-calmodulin binding. High-dose treatment begun prior to ischemia resulted in reduced cellular damage in severely ischemic hippocampal tissue, but also caused high mortality due to respiratory depression. Treatment begun 30 minutes after ischemia resulted in little histological protection but significantly improved learning ability when tested 1 month after ischemia, and did not increase mortality. Furthermore, CGS-19755, 10 mg/kg intraperitoneally, begun either before or after ischemia substantially reduced calcium influx into ischemic neurons as evidenced by reduced calcium-calmodulin binding. We conclude that CGS-19755 prevents calcium entry into ischemic neurons and may be effective therapy for very acute cerebral ischemia.