Mild hypothermia, hypertension, and mannitol are protective against infarction during experimental intracranial temporary vessel occlusion

A rabbit model of focal temporary ischemia was used to test the protection provided by mild hypothermia, hypertension, mannitol and the combination of the three methods. Twenty-four New Zealand White rabbits were divided into five groups as follows: a control group, a hypertension group (mean arterial blood pressure increased by 42 mm Hg), a hypothermic group (rectal temperature decreased by 6 degrees C), a mannitol group (1 g/kg of body weight, administered intravenously), and the triple-therapy group. The intracranial internal carotid artery, the middle cerebral artery, and the anterior cerebral artery were clipped for 2 hours and then underwent 4 hours of reperfusion. Blood pressure, rectal and brain temperature, blood glucose level, hematocrit, and arterial blood gases were monitored during the experiment. For measuring the infarction size, the brain was divided into 4-mm slices and stained with 2,3,5-triphenyltetrazolium chloride. The severity of the neuronal damage was also evaluated by conventional histological examination with hematoxylin and eosin staining. The infarct volume was 193.2 +/- 34.8 (standard error of the mean) mm3 for the control group, 32.3 +/- 22.6 mm3 for the hypertension group (P < 0.0005 versus control), 40.9 +/- 17.6 mm3 for the hypothermia group (P < 0.0005), 58.0 +/- 41.0 mm3 for the mannitol group (P < 0.005), and 0.9 +/- 0.9 mm3 for the triple-therapy group (P < 0.0001). The infarct volume of the triple-therapy group was smaller than that of the hypertension, hypothermia, and mannitol groups but the difference was not statistically significant. The combination of hypertension, mild hypothermia, and mannitol to protect against temporary focal ischemia provides a set of manipulations that is readily available for neurovascular procedures.

Technetium99m-sestamibi scanning before initial neck exploration in patients with primary hyperparathyroidism

Technetium99m (Tc) sestamibi(mibi) has been proposed as an alternative to the standard radionuclide imaging technique of thallium 201 chloride-99mTc pertechnetate subtraction scan (TTS) in patients with primary hyperparathyroidism. In the present study, mibi was evaluated as an alternative to TTS in 37 patients who had either mibi-99mTc pertechnetate subtraction scans, mibi-iodine123 (I) subtraction scans or mibi single isotope washout scans. There were 30 females and 7 males with an average age of 57 years (range, 27-78 years). Parathyroid adenomas were found in 35 patients and hyperplasia in 2. Twenty-eight mibi scans were positive and 25 of these correctly localized the parathyroid abnormality for a sensitivity of 68% (25 of 37) and a positive predictive value of 89% (25 of 28). There were 3 false-positives (8%) and 9 false-negatives (25%). The scan was not helpful in either patient with parathyroid gland hyperplasia. Mibi-123I subtraction was the most accurate scan and was diagnostic clinically in all 7 patients studied. Mibi scans were significantly more likely to identify inferior rather than superior adenomas (P = 0.01). Twenty-seven of the 37 patients also had a TTS which was correct in only 37% of cases while the mibi scan was correct in 68% (P = 0.02). However, routine use of nuclear scanning with mibi was still not supported by these data. Further clinical evaluation of various techniques may improve accuracy. Since mibi was significantly more accurate than TTS, it should be considered preferentially when radionuclide imaging is used in patients with recurrent hyperparathyroidism.

In vitro activity of A-86719.1, a novel 2-pyridone antimicrobial agent

This study evaluated the in vitro activity of A-86719.1, a novel 2-pyridone antimicrobial agent. The drug inhibited all tested members of the family Enterobacteriaceae at < or = 0.5 microgram/ml and all tested Pseudomonas aeruginosa, Burkholderia (Pseudomonas) cepacia, and Xanthomonas maltophilia strains at < or = 2 micrograms/ml. All but two strains of gram-positive bacteria were inhibited by < or = 1 microgram of the new drug per ml, including isolates highly resistant to ciprofloxacin.

Transmission at the squid giant synapse was blocked by tetanus toxin by affecting synaptobrevin, a vesicle-bound protein

1. The effect of whole tetanus toxin (TeTX) and of its light chain (TeTX L-chain) on transmitter release was determined by presynaptic pressure-injection in the squid giant synapse. 2. The results indicate that whole TeTX does not modify transmission while the L-chain blocks transmission within 20-30 min. This block does not involve changes in the sodium or potassium conductances responsible for spike generation or the voltage-dependent presynaptic calcium current responsible for transmitter release. 3. Western blotting of protein fractions from the squid optic lobe demonstrated the presence of a protein which reacted with specific antibodies against mammalian synaptobrevin, a vesicular protein. In addition, this protein was enzymatically cleaved by the L-chain component of the toxin in a similar fashion to its mammalian counterpart. 4. These results demonstrate that TeTX L-chain toxin acts directly on a squid synaptobrevin and prevents synaptic release probably by interfering with the docking-fusion synaptic vesicles at the active zone.

Single photon emission computed tomography using 99mTc-HM-PAO in the routine evaluation of Alzheimer's disease

Regional cerebral blood flow was studied in 7 patients with clinically suspected Alzheimer's disease and 10 normal controls by single photon computed emission tomography (SPECT) using HM-PAO. All patients with Alzheimer's disease and no controls had parietal lobe hypoperfusion which was usually bilateral. In patients with more severe dementia hypoperfusion extended into the frontal lobes. Parietal lobe hypoperfusion corresponds to parietal lobe degeneration which is the one of the first neocortical regions to show the typical degenerative changes of Alzheimer's disease. SPECT with HM-PAO is a non-invasive investigation available in most nuclear medicine departments and complements existing tests in the routine evaluation of patients presenting with dementia.

Translocation (X;12)(q27;q14) in a lipoma

Cytogenetic analysis by short-term culture of a lipoma from the posterior neck region of a 63-year-old man showed a t(X;12)(q27;q14) as the sole chromosomal abnormality. Rearrangement of band 12q14 is nonrandom in lipomas, although its involvement with a sex chromosome has not been reported earlier.

[F3, a fractionated extract of Astragalus membranaceus, potentiates lymphokine-activated killer cell cytotoxicity generated by low-dose recombinant interleukin-2]

Success with rIL-2 immunotherapy of human cancer appears to depend on the administration of high doses which are frequently associated with excessive toxicity. Future use of rIL-2 will require certain modifications based on the use of lower doses of rIL-2 without significant loss of antitumor efficacy. The authors tested in vitro the possibility of potentiating the activity of rIL-2 in terms of LAK cell generation. The authors hypothesized that co-incubation of LAK cell precursors with a Chinese herbal extract (F3) of Astragalus membranaceus (an immune modulator currently under study in the authors' laboratory), along with a low concentration of rIL-2 would generate levels of LAK cell activity equivalent to those generated by high concentrations of rIL-2 alone. The authors found: (1) a 10-fold potentiation of rIL-2 activity manifested by tumor cell killing activity of 80% resulting from LAK cell generation with F3 plus 100 u/ml of rIL-2 versus 76% generated by 1000 u/ml of rIL-2 alone; (2) a significant reduction in the number of effector LAK cells required for equicytotoxic reaction following LAK cell generation with F3 plus rIL-2 compared to rIL-2 alone. The authors conclude that potentiation of antitumor activity mediated by rIL-2 in low concentrations is possible by the concomitant use of another immune modulator such as Astragalus membranaceus.

Plasma concentration of atrial natriuretic peptide in different phases of Korean hemorrhagic fever

Korean hemorrhagic fever (KHF) is an epidemic viral disease characterized by high fever, hemorrhagic tendency and renal failure, and by hemorrhages of right atrium and renal medulla as well as necrosis of anterior hypophysis. Plasma immunoreactive atrial natriuretic peptide (irANP) levels of 15 patients in the oliguric phase was 94.8 +/- 8.4 pg/ml (mean +/- SEM), 80% higher than of the normal control group (53.0 +/- 4.7 pg/ml; n = 28). In the diuretic phase it declined to 63.7 +/- 5.3 pg/ml (n = 26). Plasma renin activity (PRA) in the oliguric phase was 19.0 +/- 1.3 ng AI/ml/h, and in the diuretic phase 5.3 +/- 0.9 ng AI/ml/h, significantly higher than the control value (2.5 +/- 0.1 ng AI/ml/h). Elevations of irANP and PRA were not correlated in each group. Also systemic blood pressure as well as heart beats were significantly increased in the oliguric phase. These findings suggest that the increased irANP may have resulted from increased circulatory volume and that the ANP secretory process may not be affected by the disease.

Management of airway problems in lung cancer patients using the neodymium-yttrium-aluminum-garnet (Nd-YAG) laser and endobronchial radiotherapy

This study summarizes our experience in the evolution of a management technique for unresectable or recurrent lung cancer using the neodymium-yttrium-aluminum-garnet (Nd-YAG) laser with high-dose endobronchial brachytherapy. The laser gave good palliation for hemoptysis and obstruction with a low complication rate, and the addition of endobronchial radiotherapy was a useful adjunct for maintaining airway patency. High-dose brachytherapy delivered by the Gammamed IIi remote afterloader proved to be the best method of delivering this treatment.

Tension and compression in the cytoskeleton of PC 12 neurites

We report in this article that the retraction of PC 12 neurites, unlike that of other cultured neurons, is due to tension within the neurite. Retraction is rapid and independent of metabolic energy. Transection of one arm of a branched neurite immediately causes the remaining arm to take up a new equilibrium position between attachment points. Similarly, detachment of one growth cone of a cell causes the cell body to move to a new equilibrium position between the remaining neurites. These observations provide direct evidence for the suspension of the cell soma among a network of tensioned neurites. We used retraction as an assay for neurite tension to examine the role of actin filaments and microtubules in neurite support and elongation. Our data suggest that microtubules (MTs) within PC 12 neurites are under compression, supporting tension within the actin network. Treatment of cells with drugs that disrupt actin networks, cytochalasin D or erythro-9-[3-(2-hydroxynonyl)]adenosine eliminates retraction regardless of the absence of MTs, lack of adhesion to the substratum, or integrity of the neurite. Conversely, stimulation of actin polymerization by injection of phalloidin causes retraction of neurites. Treatments that depolymerize MTs, nocodazole or cold, cause retraction of neurites, which suggests that microtubules support this tension, i.e., are under compression. Stabilization of MTs with taxol stabilizes neurites to retraction and under appropriate circumstances can drive neurite extension. Taxol-stimulated neurite extension is augmented by combined treatment with anti-actin drugs. This is consistent with the actin network's normally exerting a force opposite that of MT assembly. Cytochalasin and erythro-9-[3-(2-hydroxynonyl)] adenosine were found to increase slightly the dose of nocodazole required for MT depolymerization. This is consistent with the postulated balance of forces and also suggests that alteration of the compression borne by the microtubules could serve as a local regulator for MT polymerization during neurite outgrowth.

Isozyme patterns of Armillaria intersterility groups occurring in British Columbia

Isozyme patterns for esterase and polyphenol oxidase were determined for diploid isolates of the six Armillaria intersterility groups collected in British Columbia. Factor analysis of digitized isozyme banding patterns separated A. bulbosa, A. ostoyae, and groups V and IX of Anderson and Ullrich. Results suggest that isozyme patterns may be used to identify subgroups within intersterility groups and to identify closely related intersterility groups.

Spatial organization of axonal microtubules

Several workers have found that axonal microtubules have a uniform polarity orientation. It is the "+" end of the polymer that is distal to the cell body. The experiments reported here investigate whether this high degree of organization can be accounted for on the basis of structures or mechanisms within the axon. Substantial depolymerization of axonal microtubules was observed in isolated, postganglionic sympathetic nerve fibers of the cat subjected to cold treatment; generally less than 10% of the original number of microtubules/micron 2 remained in cross section. The number of cold stable MTs that remained was not correlated with axonal area and they were also found within Schwann cells. Microtubules were allowed to repolymerize and the polarity orientation of the reassembled microtubules was determined. In fibers from four cats, a majority of reassembled microtubules returned with the original polarity orientation. However, in no case was the polarity orientation as uniform as the original organization. The degree to which the original orientation returned in a fiber was correlated with the number of cold-stable microtubules in the fiber. We suggest that stable microtubule fragments serve as nucleating elements for microtubule assembly and play a role in the spatial organization of neuronal microtubules. The extremely rapid reassembly of microtubules that we observed, returning to near control levels within the first 5 min, supports microtubule elongation from a nucleus. However, in three of four fibers examined this initial assembly was followed by an equally rapid, but transient decline in microtubule number to a value that was significantly different than the initial peak. This observation is difficult to interpret; however, a similar transient peak has been reported upon repolymerization of spindle microtubules after pressure induced depolymerization.

Antihypertensive effect of tiapamil, a calcium antagonist. Double-blind placebo crossover study

The antihypertensive effects of intravenously and orally administered tiapamil and placebo were compared in 6 male patients (60 +/- 5 years: mean +/- SD) with mild essential hypertension (WHO classification Stage I) in a randomized double-blind crossover procedure. In the intravenous study, 1 mg/kg loading dose of tiapamil (or placebo) was followed by 50 micrograms/kg/min tiapamil or placebo over 2 h. In the oral study, the patients received placebo or approximately 6 mg/kg tiapamil. Blood pressure (BP) was determined by the Hawksley Random Zero Sphygmomanometer. Heart rate (HR) and P-R interval were derived from ECGs. Statistical significance was assessed by the paired Student's test. While intravenously administered placebo transiently increased both BP and HR, intravenous tiapamil significantly (p less than or equal to 0.05) lowered both variables. The P-R interval was also transiently but significantly (p less than or equal to 0.05) increased by intravenous tiapamil. Similarly, orally administered tiapamil showed an antihypertensive effect which was not observed with placebo. Neither HR nor P-R interval was influenced by oral tiapamil. The results suggest that tiapamil is an effective but short-acting antihypertensive agent.