Characteristics of bone mineral density and soft tissue composition of obese Japanese women: Application of dual-energy X-ray absorptiometry

We studied the characteristics of bone mineral density (BMD) and soft tissue composition in obese Japanese women using dual-energy X-ray absorptiometry. Eighty-nine women, aged 45–85 years, were divided into three groups according to their body mass index (BMI): a thin group (n = 38; BMI < 21), a standard weight group (n = 31; BMI, 21–25), and an obese group (n = 20; BMI ≥ 25). The mean BMD of the second to fourth lumbar vertebrae and BMD of the lumbar spine, thoracic spine, pelvis, legs, and ribs of the thin group were significantly lower than those of the standard weight group or the obese group (P < 0.05), whereas no significant difference in total body BMD was observed among the three groups. There was a significant difference in total and regional fat mass among the three groups (P < 0.05). Lean mass of legs and total lean mass showed a significant difference between the thin group and the obese group (P < 0.05). The results showed that obesity was associated with higher BMD of weight bearing-bones and ribs, high total and regional fat mass, and high lean mass of bilateral legs and total lean mass. We suggest that obesity may contribute to the prevention of bone loss of weight-bearing bones and ribs and muscular atrophy of the legs. Received: Sept. 30, 1998 / Accepted: Dec. 10, 1998     

Adaptive fusimotor reflex control in the decerebrate cat

The effect of electrical stimulation of cutaneous afferents in the superficial peroneal nerve on the locomotor discharges of single medial gastrocnemius gamma-motoneurones has been investigated in a decerebrate cat preparation. Units were classified as static (n=9) or dynamic (n=7) indirectly on the basis of their resting and locomotor discharge characteristics. Brief trains of stimulation, at 2 and 3xthreshold (T), were applied at rest and during locomotion. Responses were assessed by calculating the change in mean rate during the 100 ms after stimulus onset compared with a control period. At rest, static and dynamic gamma-motoneurones showed opposite responses. Static neurones were excited while inhibition was dominant with dynamic neurones. Effects were always present at 2T. During locomotion, inhibitory responses occurred with both types of gamma-motoneurone and excitation was not apparent. The inhibition of static neurones was maximum during (four units) or between (five units) EMG bursts and minimum in the opposite phase of EMG activity. For dynamic neurones, inhibition was not related to locomotor phase. Generally (six of seven units), the inhibition of dynamic gamma-motoneurones was reduced throughout the step cycle, including phases in which background discharge rates were comparable to resting levels. Latencies of response were measured from peristimulus time histograms. Subtraction of peripheral conduction times gave estimated central delays of locomotor inhibition for static (2.4+/-0.2 ms, n=6; mean+/-S.E.M.) and dynamic (2.2+/-0.2 ms, n=7) gamma-motoneurones that were not significantly different (P>0. 1) and are consistent with spinal oligosynaptic pathways. We conclude that low threshold skin afferents from the foot dorsum are capable of influencing both types of gamma-motoneurone during walking through short latency spinal inhibitory pathways. Further, a highly specific (reciprocal) control of the reflex responses of static and dynamic gamma-efferents occurs that is dependent upon behavioural context. The results are discussed in relation to cutaneous effects on gamma-motoneurones which are suggested to form an adaptive control system.     

香附水提剂对离体兔肠管活动的影响

目的：探讨香附水提剂对离体兔肠平滑肌的作用。方法：采用Magnus实验装置,使用二道仪描记离体兔肠平滑肌收缩曲线5min作为对照,然后观察药物对其作用25min后曲线变化,并与对照组比较。结果：给香附水提剂后5min离体平滑肌收缩频率及幅度降低较阿托品对照组明显;5-15min二者接近;25min后降低幅度为阿托品组1.3倍,二者比较差异显著（P＜0.01）。结论：香阳水提剂能明显抑制离体兔肠平滑肌的收缩幅度与频率,同时也能拮抗乙酰胆碱和氯化钡所致离体肠管平滑肌的兴奋作用。     

L-701,324, a selective antagonist at the glycine site of the NMDA receptor, counteracts haloperidol-induced muscle rigidity in rats

  Rationale: It has recently been suggested that the overactivity of glutamatergic neurotransmission may contribute to the pathophysiology of Parkinson’s disease. Therefore, a search for new compounds which block glutamatergic receptors and show antiparkinsonian properties in animal models of this disease seems to be justified. Objective: The aim of this study was to determine whether L-701,324 [7-chloro-4-hydroxy-3(3-phenoxy) phenylquinoline-2-(H)-one], a selective and full antagonist at the glycine site of the NMDA receptor, counteracts parkinsonian-like muscle rigidity and catalepsy induced by haloperidol in rats. Methods: The muscle tone was measured as the resistance developed to passive flexion and extension of the hind limb. Electromyographic (EMG) activity was additionally recorded in the gastrocnemius and tibialis anterior muscles. Results: L-701,324 (2.5–40 mg/kg IP) dose-dependently decreased the muscle tone enhanced by haloperidol (1–5 mg/kg IP). Likewise, the haloperidol-enhanced resting EMG activity and the EMG reflex response to passive movements were diminished by lower and almost abolished by higher doses of L-701,324. However, up to a dose of 20 mg/kg IP, L-701,324 did not influence haloperidol (0.5 mg/kg IP)-induced catalepsy. Moreover, L-701,324 (1.25–5 mg/kg IP) given alone or together with haloperidol (0.5–1 mg/kg IP) disturbed rotarod performance. Gross observation of behaviour indicated that rats injected with L-701,324 in doses equal to or higher than 5 mg/kg, alone or in combination with haloperidol, were markedly ataxic, i.e. rats showed signs of disturbed balance and loss of control over their hind limbs. Conclusions: The present study suggests that L-701,324 exhibits a beneficial action in the animal model of parkinsonian rigidity, but not that of parkinsonian akinesia. Nonetheless, this compound is not devoid of motor side-effects. Received: 1 February 1998 / Final version: 20 October 1998     

Alpha-motoneuron excitability at high altitude

Summary It has been hypothesized that chronic hypobaric hypoxia could lead to inhibition of the-motoneuron pool, thus limiting the maximal activation of working skeletal muscles. To test this hypothesis six subjects [32 (SEM 2) years] were evaluated in resting conditions, at sea level and after acclimatization at 5,050 m. The recruitment curves of the Hofmann-reflex (H-) and the direct muscle-response (M-) of the right soleus muscle were obtained by stimulating the posterior tibeal nerve with different intensities while recording the electromyogram of the soleus muscle. From the recorded data the net-motoneuron excitability (ratio of maximal H-reflex to M-response H_max : M_max ratio), the threshold and gain for both responses, obtained from linear regressions through the rising phase of the recruitment curves of both responses, as well as the latency times of both responses were determined. The latency times and the H_max :M_max ratio were unchanged at altitude. The thresholds of both responses and the gain of the M-response were unaltered. The gain of the H-response was significantly higher at altitude when compared to sea level. It is concluded that in the acclimatized subjects at rest the signal conduction velocity through the different parts of both pathways was unaltered and therefore nerve and muscle conduction velocity as well as synaptic and muscle end-plate transmission were unchanged, that the recruitment of the H-reflex was slightly facilitated after acclimatization to high altitude suggesting increased excitability of the-motoneurons, through either postsynaptic facilitatory changes in the soma or a different descending drive, and that the unchanged H_max:M_max ratio indicated no change in the net excitatory and inhibitory influences on the-motoneuron pool. The above hypothesis is thus not strengthened by the results that were, however, obtained in resting conditions.     

Editor's note for debate Sporadic dementia of Alzheimer type: Role of amyloid in etiology is challenged

Summary Alzheimer's disease is a heterogenous neurodegenerative disorder. Whereas only a minority is due to genetic abnormalities and mostly with early onset, the majority of all Alzheimer cases is sporadic and with late onset. Therefore, in the latter, age-related disturbances in cellular metabolism may come into focus with respect to the etiopathogenesis rather than the primary formation of amyloid. In this Editor's note for debate, the role of amyloid as a causative factor of sporadic Alzheimer's disease is challenged. Instead, as a possible primary abnormal event in sporadic Alzheimer's disease, the perturbations in neuronal glucose metabolism and the subsequent ATP deficit with its impacts on the secondary amyloid formation are discussed to open a new field of research and another aspect for debate.     

Autoradiography of 14C-choline uptake in endplates and skeletal muscle of mice

Summary The uptake of ¹⁴C-choline into the axonal part of the motor endplate and muscle of mouse diaphragms was investigated by autoradiography. With i. v. doses of 0.1 g/g choline chloride, the uptake into the nerve endings is fast (<2 min) and into muscle slower (>2 min). With higher doses (1.0 g/g) the uptake into muscle tissue is accelerated.The radioactivity in the endplates decreases with a halflife time of 20 min and remains constant in the muscle fibres over 60 min. Denervation by cutting the phrenic nerve reduces the uptake into endplates by 40% within 14 h, but probably induces uptake into regenerating Schwann cells during 30 days. Some compounds with choline-like structure (hemicholinium-3, decamethylen-dicholine, triethyl-choline) reduce the high-affinity uptake of choline into the nerve endings with sublethal doses, whereas tetraethylammonium and N-hydroxyethyl-4-(1-naphthylvinyl)-pyridinium, an inhibitor of cholinacetyltransferase, are less active. Half lethal doses of cocaine, imipramine and reserpine have no significant action on uptake of choline into the endplates. Chlorpromazine slightly diminishes the uptake into endplates. Chlorpromazine and imipramine reduce uptake into the muscle fibres.     

Development and inhibition of the target phenomenon in tenotomized rat muscle

Summary The sequence of development of the target phenomenon in tenotomized gastrocnemius muscle was studied: the presence of target fibres was preceded by the occurrence of contraction bands and of moth eaten appearance of the fibres. This phenomenon was far more pronounced and occurred earlier in type II than in type I fibres.This target phenomenon and the contraction artefacts could be inhibited in the tenotomized muscles by simultaneous neurotomy or immobilization of the muscle with a plaster cast. Delayed denervation inhibited also the target phenomenon, if performed less than 5 days after the tenotomy. These series of experiments seem to indicate that the target phenomenon occurs in more irritable muscle fibres and that muscular activity is needed for its development.     

Membrane structures of human oligodendroglioma

Summary Two cases of McArdle's syndrome are reported. One is a classical exaple; the other is unusual because of the in vitro presence of muscle phosphorylase activity. In the latter case. the electronmicroscopic investigation confirmed the diagnosis.The fine structural changes characteristic of this disease are summarized and it is concluded that histochemical studies alone are insufficient to exclude the diagnosis of McArdle's myopathy.     

亚热带地区哺乳妇女能量需要量的观察

以同地区的53名非哺乳育龄妇女作对照,对262名产后0～6月乳母的体重、皮脂、上臂围、基础代谢率(BMR)、能量消耗和摄入量分别进行横向和纵向观察。结果表明,产后乳母体重和皮脂厚度逐渐下降,至第4个月基本稳定,平均减重4.2kg,估计孕期的贮脂大部分已消耗。上臂围无明显变化(P>0.05)。乳母的BMR在产后第1周较高(P<0.01),1～6月无明显变化(P<0.05),但比对照组高4～20％(P<0.05)。乳母在同一标准活动耗能与对照组接近(P>0.05)。轻体力劳动乳母日均活动耗能8.360MJ,估计泌乳耗能为2.807MJ/d。乳母能量摄入量比对照组多2.259MJ/d。作者认为,亚热带产后0～6月乳母在正常哺乳情况下,头4个月每日能量需要量应在平日消耗量基础上增加1.883MJ(450kcal),后雨月增加2.720MJ(650kcal),或整个阶段平均增加2.092MJ/d(500kcal/d),但此值仍需按泌乳量和正常体重变化加以调节。