A PET study of the neural systems of stuttering

The cause of stuttering is unknown. Failure to develop left-hemispheric dominance for speech is a long-standing theory although others implicated the motor system more broadly, often postulating hyperactivity of the right (language nondominant) cerebral hemisphere. As knowledge of motor circuitry has advanced, theories of stuttering have become more anatomically specific, postulating hyperactivity of premotor cortex, either directly or through connectivity with the thalamus and basal ganglia. Alternative theories target the auditory and speech production systems. By contrasting stuttering with fluent speech using positron emission tomography combined with chorus reading to induce fluency, we found support for each of these hypotheses. Stuttering induced widespread overactivations of the motor system in both cerebrum and cerebellum, with right cerebral dominance. Stuttered reading lacked left-lateralized activations of the auditory system, which are thought to support the self-monitoring of speech, and selectively deactivated a frontal-temporal system implicated in speech production. Induced fluency decreased or eliminated the overactivity in most motor areas, and largely reversed the auditory-system underactivations and the deactivation of the speech production system. Thus stuttering is a disorder affecting the multiple neural systems used for speaking.     

Nasopharyngeal Castleman's disease

A 19-year-old male was admitted to our clinic because of nasal obstruction and intermittent postnasal drip of 3 to 4 years' duration. Physical examination revealed a wide-based, smooth-surfaced nasopharyngeal tumor which was suspected to be a nasopharyngeal angiofibroma after examination of computed tomographic scans and an angiogram. However, after the tumor was removed by surgical excision via a transpalatal approach, the pathologic examination revealed Castleman's disease of the hyaline-vascular type. There was neither evidence of recurrence nor nasal problems at 4 years' follow-up. To our knowledge, Castleman's disease, or angiofollicular lymph node hyperplasia, may present as a local or generalized tumor-like condition, usually in the chest or abdomen, and may involve both the lymph nodes and non-nodal tissues. A review of previous articles reveals that there has not been any report of Castleman's disease found in the nasopharynx. This rare disorder is presented and discussed.     

Absorption of isomeric, palmitic acid-containing triacylglycerols resembling human milk fat in the adult rat

The effect of the positional distribution of palmitic acid (16:0) in triacylglycerols (TAG) on 16:0 apparent absorption in adult rats was investigated. The rats were fed two diets which contained 30 energy % as fat with identical total fatty acid compositions, both containing 30% 16:0. The Betapol diet contained TAG with 73% of total 16:0 in the sn-2 position, the control diet contained TAG with 6% of total 16:0 in the sn-2 position. After six weeks on these diets, the rats were killed two or six hours after the last meal, and the small intestine was removed, cut into 10-cm segments, and the fatty acid composition of the segment's contents was determined. At both time points the amount of 16:0 in the intestinal segments starting at 40 cm from the stomach was much lower in the animals fed Betapol than in the animals fed the control diet. Overall absorption of 16:0 and stearic acid was significantly greater in the Betapol group. Absorption of oleic and linoleic acid from the small intestine was similar in both groups, although the overall absorption was significantly greater in the animals fed Betapol. Total fat absorption was significantly higher in the Betapol-fed rats than in the control-fed rats. No effect on calcium and nitrogen absorption, on plasma total cholesterol and TAG levels, and on bodyweights (growth) was seen. The data demonstrate that the positional distribution of the fatty acids in the TAG molecule affects the site of absorption in the small intestine and particularly the net absorption of saturated fatty acids.     

2H( gamma,p)n cross section between 20 and 440 MeV

Rate control in acetylcholinesterase (AChE) involves a single anionic site whose anionic center controls rate-related biochemical and conformational changes in the E (free enzyme) and EA (acylated enzyme) conformers. Change in conformer structure and biochemistry affect binding, acylation, and hydrolysis. It is significant that the anionic-esteratic intersite distance is not altered during conformer change as E is converted to EA. In this enzyme system, cationic acetylcholine and anionic AChE are true structural, functional, and biochemical counterparts. The anionic center in the E conformer lies at the bottom of a sterically restricted, hydrophobic cleft < 8 A wide at the top and > 3 A wide at the bottom, while the anionic center in the EA conformer is relatively open. It is characterized by a decrease in the relative binding of hydrophobic cations and by an ability to bind large organic cations. Binding of acetylcholine, H+, or organic cations at the anionic site controls k2(acylation) in the E conformer and k3(hydrolysis) in the EA conformer. Acetylcholine binding forms the ES complex in which the cation maximizes k2. In the EAS complex, the cation reduces k3 and provides allosteric control. Anionic site structure and biochemistry and the effect of pH on k2 and k3 differentiates AChE from butyrylcholinesterase. This comprehensive study of kinetic and thermodynamic processes in AChE was made possible by the synthesis and/or use of families of over 30 cationic and acylation probes of known stereochemistry. They act as rulers of the E and EA conformers of AChE and provide comparative data on kinetic-based and thermodynamic-based constants. Cationic inhibitors affect decarbamylation rates in AChE and provide an additional set of comparative data related to the mechanism of substrate hydrolysis by AChE. Acridine araphanes are unique neural receptor and cholinergic enzyme probes. Their parallel plane and coplanar conformations are related to bridge length. Two parallel plane acridine araphanes are pure uncompetitive inhibitors of AChE. Scatchard plots of the binding of methylacridinium and 9-aminoacridine with the E conformer and 9-aminoacridine with the EA conformer indicate binding at a single anionic site. No ternary complex (EII or EAII) from two-site binding was detected. In AChE, nonspecific, low-level binding at surface ionic and hydrophobic areas is ubiquitous. Binding affinity differences greater than two orders of magnitude distinguish binding at the anionic site from low level binding at surface moieties. Surface binding provides environmental and stability changes in the enzyme but does not modify the fundamental biochemistry of the E and EA conformers.     

Positron emission tomography for the evaluation of pancreatic disease

Efficient techniques for native-labeling of amino acids have been combined successfully with emission tomography to yield significant improvements in pancreatic imaging. Carbon-11-labeled tryptophan appears to be the best agent available currently for imaging the pancreas. Optimum scanning times begin 30 min after tracer administration. Positron emission tomography with 11C-tryptophan is capable of defining both morphological and functional alterations in the pancreas. Tumors as small as 2 cm in diameter can be detected, but reliable differentiation of pancreatic cancer from pancreatis may not be possible even with this improved imaging technique. Longitudinal multiplane emission tomography in single-photon mode with the Pho/Con provides an efficient and satisfactory approach to pancreatic imaging with the positron-emitting radiopharmaceuticals.     

Predictors of weight change following smoking cessation

Smoking behavior and weight change over a 5-year period were studied in 1,749 adult males of the Normative Aging Study. While men who quit smoking generally gained more weight than those in other smoking categories, 36% either lost weight or maintained the same weight after quitting. The major research focus was to predict the direction of weight change after smoking cessation. Among the characteristics most related to weight gain after quitting were heavier tar consumption, younger age, and leanness of body build. Conversely, traits related to weight loss were lighter smoking, older age, and stoutness of build.     

beta-Amyloid precursor protein isoforms show correlations with neurones but not with glia of demented subjects

Post-mortem cerebral cortex from 15 demented patients was specially collected to minimise autolysis and two membrane fractions and one soluble fraction were quantitatively examined for the major species of beta-amyloid precursor protein (APP) of high apparent molecular mass (> or = 80 kDa) together with the major mRNA species encoding APP isoforms. The number of pyramidal neurones and astrocytes, putative biochemical indices of interneurones and pyramidal neurones, and choline acetyl transferase activity were also determined. Multiple regression analysis has been used to investigate intercorrelations of APP species with biochemical and morphometric measures, free of any effects of confounding demographic variables. Subjects with Alzheimer's disease showed a loss of cholinergic activity and D-aspartate uptake compared with patients with other causes of dementia. The major finding of the study is that measures of neurones rather than astrocytes most closely correlate with the concentration of APP. Pyramidal cell numbers were positively correlated with mRNA for APP695. APP in the soluble fraction showed a negative correlation with pyramidal cell numbers and cholinergic activity. These results indicate that neurones within the cerebral cortex are the major source of APP, and that secretion of APP is dependent upon cortical pyramidal neuronal activity and cholinergic activity.     

Chemokine-induced fever: intracerebroventricular actions of MIP-1 and MIP-1 alpha in rats

The central pyrogenic actions in the rat of doublet macrophage inflammatory protein-1 (MIP-1) and MIP-1 alpha were determined by their intracerebroventricular infusion. Doses of 560 pg and 11.2 ng of MIP-1 or 10.0 ng MIP-1 alpha infused into the third cerebral ventricle induced a long lasting fever. However, MIP-1 alpha was much less potent than MIP-1 in terms of intensity and longer latency. Overall, these cytokines are pyrogenic when acting on the walls of the third ventricle; however, a dose 10 times greater than that injected directly into the anterior hypothalamus is required to evoke fever, as based on earlier experiments. Finally, circulating MIP-1 could act centrally by its entry through the choroid plexus into the ventricular system of the brain.     

The effect of adrenergic agonists on the systemic response to hemorrhage

An in vivo antitumor screening of extracts of Gomphrena martiana indicated positive activity in the petroleum ether extract, and its further bioactivity-directed fractionation resulted in a lipophilic flavonoid fraction. Upon inoculation of various doses of 5,6,7-trisubstituted flavones on two murine tumor lines, Sarcoma 180 and Ehrlich's carcinoma, a decrease of tumor growth was observed. An in vitro KB cultured cell screen indicated cytotoxicity.     

Lumbosacral movement in the sit-and-reach and in Cailliet's protective-hamstring stretch

STUDY DESIGN: This study analyzed movement characteristics of subjects as they performed two different hamstring stretching activities. OBJECTIVES: The study determined if there were differences in lumbosacral movement as the subjects performed the two stretches. SUMMARY OF BACKGROUND DATA: Cailliet contends that his protective hamstring stretch is less apt to be stressful to the structures of the spine than is a more commonly done sit-and-reach stretching activity. No previous biomechanical investigation has tested his contention. METHODS: Lumbosacral movement was measured with an Ady-Hall lumbar monitor as 40 university students (20 males, 20 females) performed a popular sit-and-reach test and a sit-and-reach test that subscribed to Cailliet's protective hamstring stretch protocol. RESULTS: Lumbosacral movement was almost identical in the two stretching activities. CONCLUSIONS: If lumbosacral movement is the only criterion to consider in evaluating the safety of these two stretching activities, it makes little difference which activity is chosen. If moment of inertia were the dependent variable rather than lumbosacral movement, possibly one activity may be less stressful to the structures of the spine than the other.