Hemodynamics and blood flow distribution following prolonged circulation at 5 degrees C.

Circulation was maintained in profoundly hypothermic dogs for 8 h at temperatures below 10 degrees C. During cooling to 5 degrees C cardiac output and blood pressure decreased and peripheral resistance rose. Thereafter, circulatory dynamics remained relatively stable over the next 6 h with a gradual decline in blood pressure. The proportion of blood flow to the heart and brain increased with cooling and remained elevated throughout the hypothermia period. Despite continued circulation, pulmonary edema developed after 5-7 h and the dogs were nonviable when rewarmed.     

Nucleotide Sequence of the 4.3 kbp BamHI-N Fragment of Fowlpox Virus FP9

Nucleotide sequence analysis of the 4.3 kbp BamHI-N fragment of the fowlpox virus (FPV) genome revealed that it encodes 7 proteins with homology to vaccinia virus (VV) E11L, E10R, O1L, O3L, I1L, I2L and I3L encoded proteins. No evidence of FPV homolog of VV O2L could be found. This revised version was published online in July 2006 with corrections to the Cover Date.     

The role of the thalamic reticular neurons in alpha- and gamma-oscillations in neocortex: a mechanism for selective perception and stimulus binding

The long-term objective is to understand how large masses of neurons in the brain process information during various learning and memory paradigms. Both time- and space-dependent processes have been identified in animals through computer-based analytic quantifications of event-related extracellular potentials. New nonlinear analyses have been introduced that presume that the fine-grain variation in the signal is determined and patterned in phase-space. Some neurons in the primary visual cortex manifest gamma-band oscillations. These cells show both a nonspecific phase-alignment (response synchrony) and a specific tuning (orientation tuning) when stimuli are presented to their receptive fields. This dual regulation of the sensory cells is proposed to underlie stimulus binding, a theoretical mechanism for "object" perception. Nonlinear analytic results from gamma-activities in a simple model neuropil (olfactory bulb) suggest that neuroplasticity may arise through self-organization, a process in which a nonlinear change in the dynamics of the oscillatory field potentials is the hallmark. This self-organization may follow simple dynamical laws in which global cooperativity among the neurons is transiently brought about that, over trials, results in enduring changes in the nonlinear dynamics of some neurons. In conclusion, the sculpturing of the synaptic throughput in the sensory cortex (stimulus binding) may be associated with the irregular phases of the gamma-activities and may result from both specific and nonspecific systems operating together in a nonlinear self-organizing manner.     

The adaptation of the plaque reduction assay for measuring specific cytotoxic cells in limiting dilution cultures

The use of the original haemolytic plaque reduction technique to measure cytotoxic T lymphocytes (CTL) has been developed further as a rapid screening assay, particularly suitable for limiting dilution analyses. Using hybridoma cells as targets, the cytotoxicity has been measured by the loss of haemolytic plaque formation and by the reduction of the amount of haemolytic monoclonal antibody secreted from viable target cells into the assay supernatants. The assessment of large numbers of cytotoxic samples has been greatly facilitated by quantitating the amount of haemoglobin released in the assay with an automated microELISA multiscanner and by scoring visually using a modification of the spot test. Using these new techniques, relatively high frequency estimates of cytotoxic cell precursors in an allogeneic response (1 in 462 spleen cells) and an anti-fluorescein response (1 in 3970 spleen cells) were obtained.     

Differential distribution of spinal cord field potentials

Summary Electrical stimulation of the sural, superficial peroneal and plantar nerves in anesthetized cats produces a sequence of potentials in the spinal cord lumbosacral enlargement. The distributions of the spinal cord dorsum negative intermediary potential (N1 wave) and of the associated field potential recorded in depth from the spinal gray matter were mapped. The N1 wave produced by the sural nerve was largest at the junction of the S1 and L7 segments, whereas that evoked by the other two nerves was maximum in L6 and L7. The field potentials recorded in depth also showed a differential distribution. The maximum negativity during phase 2, corresponding to the N1 cord dorsum potential, was found to lie laterally in the dorsal horn when the sural nerve was stimulated, but medially when the plantar nerve was activated. The superficial peroneal nerve produced its largest negative field potential in the central region of the dorsal horn. The negative field potentials from the sural and superficial peroneal nerves were not as well separated spatially from each other as they were from the potential evoked by the plantar nerve.     

Identification of MEN1 gene mutations in sporadic carcinoid tumors of the lung

Lung carcinoids occur sporadically and rarely in association with multiple endocrine neoplasia type 1 (MEN1). There are no well defined genetic abnormalities known to occur in these tumors. We studied 11 sporadic lung carcinoids for loss of heterozygosity (LOH) at the locus of the MEN1 gene on chromosome 11q13, and for mutations of the MEN1 gene using dideoxy fingerprinting. Additionally, a lung carcinoid from a MEN1 patient was studied. In four of 11 (36%) sporadic tumors, both copies of the MEN1 gene were inactivated. All four tumors showed the presence of a MEN1 gene mutation and loss of the other allele. Observed mutations included a 1 bp insertion, a 1 bp deletion, a 13 bp deletion and a single nucleotide substitution affecting a donor splice site. Each mutation predicts truncation or potentially complete loss of menin. The remaining seven tumors showed neither the presence of a MEN1 gene mutation nor 11q13 LOH. The tumor from the MEN1 patient showed LOH at chromosome 11q13 and a complex germline MEN1 gene mutation. The data implicate the MEN1 gene in the pathogenesis of sporadic lung carcinoids, representing the first defined genetic alteration in these tumors.      

Variations in the density of bone cement after centrifugation

Barium sulfate added to bone cement to provide radiopacity has a density about four times greater than that of polymerized radiolucent bone cement. Because centrifugation might make a clinically significant change in the distribution of barium sulfate, this process was studied. Radiolucent and radiopaque Simplex-P bone cement (Howmedica, Inc., Rutherford, New Jersey) were mixed with and without cooling and centrifuged for two or four minutes at 2,000 g or 1,000 g (gravity acceleration). The density of sections of the hardened bone cement was measured using the Archimedes principle. Erythromycin and colistin were added to cement batches to test whether or not centrifugation affected the distribution of antibiotics. Direct and radiographic observation and density measurements (cooled specimens, 2,000 g, p less than 0.01) verified that barium sulfate does accumulate at the bottom of the centrifugation tubes. Thin sections of the bone cement revealed that only larger particles (20-100 micron) of barium sulfate were deposited at the bottom. No evidence of redistribution of antibiotics after centrifugation was seen. It is recommended that Simplex-P bone cement be reformulated to eliminate concern about inhomogeneities that arise from centrifugation. Further, it is recommended that cooled, centrifuged antibiotic cement be used for long-stem revision hip surgery, where longer setting times are necessary, and room temperature cement for "fresh" hip surgery. A total centrifuge time of two minutes with a 2,000 g maximum force is recommended.