Biomedical subjects

P Ganter

Publications and source records attributed to P Ganter.

At least 19 recordsLinked to original sources

PubMed2000

Distinct frequency preferences of different types of rat hippocampal neurones in response to oscillatory input currents.

1. Coherent network oscillations in several distinct frequency bands are seen in the hippocampus of behaving animals. To investigate how different neuronal types within this network respond to oscillatory inputs we made whole-cell current clamp recordings from three different types of neurones in the CA1 region of rat hippocampal slices: pyramidal cells, fast-spiking interneurones and horizontal interneurones, and recorded their response to sinusoidal inputs at physiologically relevant frequencies (1-100 Hz). 2. Pyramidal neurones showed firing preference to inputs at theta frequencies (range 2-7 Hz; n = 30). They showed subthreshold resonance in the same frequency range (2-7 Hz; mean 4.1 +/- 0.4 Hz; n = 19). 3. Interneurones differed in their firing properties. Horizontal interneurones in the stratum oriens showed firing preference to inputs at theta frequencies (range 1.5-10 Hz; n = 10). These interneurones also showed resonance at low frequencies (range 1-5 Hz; mean 2.4 +/- 0.5 Hz; n = 7). In contrast, fast-spiking interneurones with cell bodies in the pyramidal cell layer fired preferentially at input frequencies in the gamma band (range 30-50 Hz; n = 10/12). These interneurones showed resonance at beta-gamma frequencies (10-50 Hz; mean 26 +/- 5 Hz; n = 7/8). 4. Thus, in the hippocampus, different types of neurones have distinct frequency preferences. Therefore, in the CA1 layer of the hippocampal network, a compound oscillatory input may be segregated into distinct frequency components which are processed locally by distinct types of neurones.

Action Potentials↗

PubMed1999

Spinal cord axonal loss in multiple sclerosis: a post-mortem study.

There is increasing interest in the contribution that axonal damage may make to clinical disability in multiple sclerosis (MS). The present study reports a post-mortem examination of the area occupied by the lateral white matter columns of the spinal cord and nerve fibre density in the corticospinal tracts at C3 and T2 in 23 males and 20 females with MS, who lacked plaques at these levels, and in 31 controls who, although most had had some neurological disease, showed no sign of cervical or spinal cord thoracic disease. The lateral column cross-sectional area, measured by low power image analysis of the outlined lateral columns, was reduced in MS by 17% at C3 and 21% at T2 in males and by 13% at C3 and 18% at T2 in females. These reductions were significant at both levels in males (P<0.004 at C3 and P<0.009 at T2 ) but only at T2 in females (P<0. 03). The nerve fibre density, measured by automatic image analysis of x200 microscopic fields in the region occupied by the crossed pyramidal tracts, was reduced by 41% at C3 and 42% at T2 in males and by 19% at both C3 and T2 in females. These reductions were likewise significant at both levels in males (P<0.003 and P<0.000 at C3 and T2, respectively) and T2 only in females (P<0.045). In MS, nerve fibre density was significantly lower at C3 (P<0.004) and T2 (P<0.000) in males than females. No differences were seen in these parameters between males and females in controls. The reductions in total nerve fibre densities were entirely accounted for by reductions in small nerve fibres (cross sectional area less than 5 microm2 ). No significant reductions were seen in large fibre (cross sectional area 5 microm2 or more) densities. It is concluded that substantial axonal loss and spinal cord lateral column white matter atrophy occur at C3 and T2 in MS, and that these changes can be detected in some patients from early in the course of the disease.

Adult↗

PubMed1975

[Arrector muscle in patients with scleroderma. Histological and histo-enzymological study].

In a previous paper, we have found, at post-mortem examination of three cases of scleroderma, the oesophageal smooth muscle alterations already predicted by physiologists and reported by Treacy. These lesions mostly consist of a loss of the staining properties of the differenciated cytoplasm of the muscle cell, preceding any appearance of interstitial fibrosis. We have already reported these muscle lesions at all other levels of the digestive tract (stomach, small and large bowels), and also in the bladder muscle. In the present study, we have attempted to precise these notions in biopsies and have studied the arrector pili muscles in normal skin of 13 sclerodermic patients by means of histochemical (Regaud, Mallory, etc. ...) and enzyme stains. In all cases, we have been able to identify morphological alterations of the muscle fiber, mostly consisting in an irregular pattern of enzyme properties, especially when diaphorases, dehydrogenases and ATP ases were concerned. This work seems to confirm that the primary site of the sclerodermal lesions is situated in the smooth muscle fiber.

Adenosine Triphosphatases↗

PubMed1973