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[The cytomorphological diagnosis of benign tumors of the peripheral nervous system].

Results of cytologic examination of punctates, imprints and scrapings as well as histologic sections of benign tumors of peripheral nerves surgically removed from 95 patients were used to study peculiarities of cytologic appearance and develop criteria for cytologic identification of the nature and histogenesis of those tumors. The analysis outlined the role of cytologic examination of punctates in complex preoperative diagnosis of peripheral nerve tumors. The procedure established the benign nature of tumor in 75.5% of cases whereas its histologic pattern was identified in 55.5%.

Biopsy, Needle↗

Tachykinins as modulators of the micturition reflex in the central and peripheral nervous system.

In the normal urinary bladder, tachykinins (TKs) are expressed in a population of bladder nociceptors that is sensitive to the excitatory and desensitizing effects of capsaicin (i.e., capsaicin-sensitive primary afferent neurons (CSPANs)). Several endobiotics or xenobiotics excite CSPANs and release TKs and other mediators at both the peripheral and spinal cord level. The peripheral release of TKs determines a set of responses (known as neurogenic inflammation) that includes vasodilatation, plasma protein extravasation, smooth muscle contraction and stimulation of afferent nerves. Following chronic inflammation, both immune cells and capsaicin-resistant sensory neurons can de novo express TKs: whether these pools of TKs are releasable and contribute to inflammatory processes is presently unsettled. At the spinal cord level, the release of TKs contributes in determining an altered pattern of vesicourethral reflexes in response to nociceptive stimulation of the bladder by conveying: (a) the afferent transmission to supraspinal sites, and (b) descending or sensory inputs to the sacral parasympathetic nucleus (SPN). Recent evidence also attribute a synergetic role of TKs in the supraspinal modulation of the sensory arm of the micturition reflex. The overall available information suggests that TK receptor antagonists may affect bladder motility/reflexes which occur during different pathological states, while having little influence on the normal motor bladder function.

Animals↗

Cloning of a big tau microtubule-associated protein characteristic of the peripheral nervous system.

Microtubule-associated protein tau consists in brain of a series of isoforms of 48- to 67-kDa apparent molecular mass that are encoded by mRNAs of approximately 6 kilobases (kb) and that are generated from a single gene by alternative splicing. Previously, a tau-like protein of 110-kDa apparent molecular mass was described in peripheral ganglia and in peripheral neuronlike cell lines. We now report the cloning and sequencing of a rat cDNA encoding this big tau. The corresponding protein contains sequence identical to the longest of the previously cloned small tau isoforms but with an additional 254 amino acid insert in the amino-terminal half. Big tau is produced from an 8-kb mRNA generated by alternative splicing from the same gene that encodes small tau. Production of big tau from the cloned sequence gives a protein of 110-kDa apparent molecular mass that aligns on SDS/PAGE with big tau protein extracted from peripheral ganglia. RNA blots show that in peripheral ganglia from adult rats only the 8-kb mRNA band corresponding to big tau is found, whereas in ganglia from newborn rats both 6- and 8-kb tau mRNA bands are found. In tissues from the central nervous system only the 6-kb mRNA band can be detected. Big tau protein is therefore produced specifically in the peripheral nervous system, and it will be interesting to see whether further molecular differences between the two major divisions of the vertebrate nervous system will be discovered.

Amino Acid Sequence↗

Effects of spontaneous chronic hypoglycemia on central and peripheral nervous system in insulinoma patients before and after surgery: a neurophysiological follow-up.

To investigate the effects of spontaneous chronic hypoglycemia on the peripheral and central nervous system, a multimodal neurophysiological evaluation [median somatosensory (mSEP), brain stem auditory (BAEP), and visual (VEP) evoked potentials recordings] was performed in seven insulinoma patients before and 3 and 6 months after surgical removal of tumor. Before surgery, mSEP findings showed abnormal reduction in peripheral wrist-Erb conduction velocity in three patients as well as a pathological increase in Erb-N13, N13-N20, and Erb-N20 conduction times in five cases. BAEP and VEP recordings gave pathological results in two patients. Moreover, during hypoglycemia, the III-V and I-V interpeak latencies of BAEPs were significantly prolonged (P < 0.01 and P < 0.005, respectively) compared to recordings in euglycemia. After 6 months, a mSEP recovery, even if partial was noted in four patients, BAEPs were normalized in one case, and VEPs were unmodified. Compared to presurgery data, these recordings showed a significant (P < 0.05), but incomplete, shortening of BAEPs (III-V and I-V interpeak latencies) and mSEPs (Erb-N13 and Erb-N20 conduction times). Our findings demonstrate that multiple and selective neurophysiological abnormalities are present in insulinoma patients, confirm that hypoglycemia impairs suddenly brain stem function, and show that after tumor removal, long recovery times for improvement of some neurophysiological anomalies are requested.

Adolescent↗