Monitoring and cerebral protection during carotid endarterectomy.

Two recently published multicentre trials have confirmed the overall benefit of carotid endarterectomy in symptomatic patients with severe carotid artery disease. The key to improving further the long-term advantages of carotid endarterectomy, however, remains the continued reduction of the initial operative risk. While the principal responsibility for this continues to be borne by the surgeon, specifically in reducing technical error, the time is perhaps approaching when he or she might also be able to apply some of the recent advances in cerebrovascular research to reduce operative morbidity still further in the future. This article summarizes the aetiology and pathophysiology of operation-related neurological deficits and reviews current approaches towards intraoperative monitoring, cerebral protection and assessment of quality control.     

Desenkephalin-gamma-endorphin is an antagonist of the hyperactivity response induced by infusion of dopamine into the nucleus accumbens of rat and ventral striatum of marmoset

The ability of desenkephalin-gamma-endorphin (DE gamma E; ORG5878) to antagonise a raised limbic dopamine function was investigated in the rat and common marmoset. Dopamine was infused for 13 days directly into the nucleus accumbens of the rat and ventral striatum of the marmoset and increased locomotor activity. Such increases in both the rat and marmoset were antagonised by the subcutaneous injection of DE gamma E, administered in a range 10-500 micrograms/kg (t.i.d.), during the 13 day period of infusion of dopamine. Treatment with dopamine alone or in combination with DE gamma E failed to influence the level of spontaneous locomotor activity after discontinuing treatment. In contrast, in experiments performed in the rat, the level of spontaneous locomotor activity was increased 2- to 3-fold after cessation of a regimen of infusion of dopamine and haloperidol. The increases in activity were antagonised by DE gamma E (50 and 100 micrograms/kg t.i.d., s.c., for 2 days). In additional experiments in the marmoset, using animals initially selected as "high activity" responders to challenge with (-)N-n-propylnorapomorphine, the infusion of dopamine caused a reversal in responsiveness to the stimulant effects of (-)N-n-propylnorapomorphine on locomotor activity some 2-4 weeks after discontinuing the infusion of dopamine. The administration of fluphenazine (0.01-2.5 mg/kg b.d.), during the infusion of dopamine, failed to prevent the subsequent change in responsiveness to (-)N-n-propylnorapomorphine, whereas a regimen of dopamine and DE gamma-E (25-100 micrograms/kg t.i.d.) prevented such changes.(ABSTRACT TRUNCATED AT 250 WORDS)     

Megakaryocytes in pleural and peritoneal fluids: prevalence, significance, morphology, and cytohistological correlation.

Over a period of 22 years, 4844 pleural and peritoneal fluids from 3279 patients were examined cytologically. Megakaryocytes were found in the fluids from five patients. The clinical diagnoses in the five patients were agnogenic myeloid metaplasia, chronic myeloid leukaemia, and lymphocytic lymphoma. All of these patients had persistent serous effusions. Megakaryocytes in serous fluids occurred in three forms: (1) a large type with abundant cytoplasm and multilobed nuclei, (2) a smaller type with a high nucleocytoplasmic ratio and unlobed nuclei, and (3) anucleate cytoplasmic masses. Foci of agnogenic myeloid metaplasia found on the serous surfaces at necropsy of two patients contained megakaryocytes similar to those in the corresponding effusions. The clinical course of our patients confirmed that the presence of megakaryocytes in serous fluids signifies an advanced haematopoietic malignancy.     

Intracellular free Ca2+ fluxes and responses to phorbol ester in T lymphocytes from healthy elderly subjects.

A group of healthy elderly subjects (greater than or equal to 75 years) was selected by the strict criteria of the SENIEUR protocol, and compared with healthy young (less than or equal to 35 years) volunteers. Mitogenic responses of peripheral blood mononuclear cells to phytohaemagglutinin and anti-CD3 were significantly reduced in the elderly (P less than 0.0002), thereby confirming that even though in perfect health, elderly individuals show impaired cell-mediated immunity. However, no abnormality of intracellular free Ca2+ fluxes could be detected in purified T cells from the elderly subjects when stimulated with anti-CD3 antibody. Nevertheless, both the proliferative responses of purified T cells to phorbol ester and calcium ionophore (Ionomycin) and the phorbol ester-induced inhibition of the Ca2+ response were defective in the elderly subjects (P less than 0.003 and P less than 0.0002, respectively). These data suggest that signal transduction and the generation of second messengers proceed normally in T cells from the elderly, but downstream events mediated by activation of protein kinase C are dysfunctional.     

A Parametric Approach to Measuring Cerebral Blood Flow Autoregulation from Spontaneous Variations in Blood Pressure

Autoregulation maintains cerebral blood flow (CBF) almost constant in the face of changes in arterial blood pressure (ABP). Tests for impairment of this process using only spontaneous fluctuations in ABP, without provoking large variations, are of great clinical interest, and a range of different approaches have previously been applied. Extending earlier work based on linear filters, we propose a simple parametric method using a first order finite impulse response filter. We evaluate the method on ABP and CBF velocity [(CBFV), from trancranial Doppler ultrasound] signals collected in 60 patients with stenosis or occlusion of the carotid arteries. Data were collected during the inspiration of ambient air, a 5% CO2/air mixture, and finally the return to ambient air. Equivalent data were collected in 15 normal subjects. The filters estimated from the data segments with constant inspiratory pCO2 showed the expected high-pass characteristic, which was reduced during hypercapnia and also in patients. Highly significant correlation between the filter parameters and cerebrovascular reactivity (percent increase in CBFV per unit change in end-tidal pCO2) gives further evidence that the filters reflect autoregulation. The method allows simple parametrization of the dynamic autoregulatory responses in CBFV, and the analysis of short (1 min) data segments. © 2001 Biomedical Engineering Society. PAC01: 8719Uv, 4762+q, 4380Qf     

Detection of chromosomes and estimation of aneuploidy in human spermatozoa using fluorescence in-situ hybridization

The development and application of fluorescence in-situ hybridization (FISH) has opened the way for comprehensive studies on numerical chromosome abnormalities in human spermatozoa. FISH can be rapidly applied to large numbers of spermatozoa and thus overcomes the major limitation of karyotyping spermatozoa after penetration of zona-free hamster oocytes. The simultaneous hybridization of two or more chromosome-specific probes to spermatozoa and subsequent detection of the bound probes using different fluorescent detection systems enables two or more chromosomes to be localized simultaneously in the same spermatozoon and provides a technique for undertaking reasonable estimates of aneuploidy. The most commonly used probes are those which bind to the centromeric region of specific chromosomes. Most studies to date have concentrated on estimating aneuploidy in spermatozoa from normospermic men, although reports are beginning to appear on aneuploidy in spermatozoa from subfertile and infertile men. Multi- probe FISH studies have generally reported disomy (hyperhaploidy) estimates of 0.05-0.2% per chromosome. There is preliminary evidence that some chromosomes such as X, Y and 21 are predisposed towards higher rates of non-disjunction during spermatogenesis. There are also suggestions of inter-donor variability in aneuploidy frequencies for specific chromosomes, although this requires confirmation in larger studies. While FISH is clearly a powerful technique that has many applications in reproductive medicine, it must also be realized that it does have limitations and the technology itself is still evolving and has yet to be fully validated on spermatozoa.      

Identification of canine coronavirus strains from feces by S gene nested PCR and molecular characterization of a new Australian isolate

A nested PCR (nPCR) assay for the detection of canine coronavirus (CCV) in fecal samples is described. The target sequence for the assay was a 514-bp fragment within the spike (S) glycoprotein gene. The sensitivity of the assay is extremely high, detecting as little as 25 50% tissue culture infective doses per g of unprocessed feces. A clinical trial using dogs challenged orally with CCV SA4 and CCV NVSL was used to compare viral isolation and the nPCR assay as detection techniques over a 2-week period of infection. Virus isolation detected CCV shedding from day 4 to 9 postchallenge, while the nPCR assay detected CCV shedding from day 4 to 13 postchallenge. Cloning and sequencing of the nPCR assay product enabled investigation of the evolutionary relationships between strains within the S gene. The simple and rapid procedure described here makes this assay an ideal alternative technique to electron microscopy and viral isolation in cell culture for detection of CCV shedding in feces. The described assay also provides a method of identifying new strains of CCV without the complicated and time-consuming practice of raising antibodies to individual strains. This is illustrated by the identification, for the first time, of an Australian isolate of CCV (UWSMN-1).     

Interleukin-2-dependent control of disease development in spontaneously diabetic BB rats.

Long-term treatment with recombinant interleukin-2 (IL-2) of diabetes-prone BB rats had contrasting effects in two different BB rat sublines. Diabetes development was enhanced in the subline with a low intrinsic diabetes risk and suppressed in the subline with a high diabetes risk. IL-2 treatment started between 35 and 42 days of age and lasted for 3 months. In subline 1, diabetes incidence increased from 23% to 53% (P less than 0.01), in subline 2 it decreased from 73% to 32% (P less than 0.01). The two sublines differed in serum levels of factors controlling IL-2 synthesis and activity. Mean IL-2 inhibitory activity was higher in subline 2 (between 140% and 290% of levels in subline 1, P less than 0.01). Conversely, mean concentrations of thymosin alpha 1 and beta 4 were higher in subline 1 (between 140% and 200% of levels in subline 2, P less than 0.01). Thus the two sublines differ in their response to exogenous IL-2 and also in serum levels of mediators affecting availability of IL-2. We conclude that an internal network of hormonal factors, including IL-2, contributes to the control of diabetes development in the BB rat.