Response of delta (0-3 Hz) EEG and eye movement density to a night with 100 minutes of sleep

In one of a series of experiments aimed at gathering the empirical data required to formulate mathematically our recovery model of sleep, we recently (1) measured the increase in delta electroencephalogram (EEG) following one night of total sleep deprivation (TSD). We found that the delta rebound was confined to the first non-rapid eye movement period (NREM-P1) of recovery sleep; this unexpected result was documented with direct computer measurement of 0-3 Hz EEG, as well as with visual scoring of stages 3 and 4. We also found a robust decrease in eye movement density during the second and third REM periods, which we hypothesized to be due to the increased depth of recovery sleep. In the present experiment, we awakened young adult subjects after 100 min of sleep, a duration that includes the first cycle for this age group, and analyzed visual and computer measures of delta and eye movement density during recovery sleep. We again found eye movement density to be significantly reduced in REM-P2 and P3, but to a lesser degree than after total sleep deprivation, a condition that may be presumed to produce a greater increase in sleep depth. Delta increases were again limited to the first cycle, although all subjects completed this cycle on the 100-min night. The major difference between recovery sleep patterns following the total deprivation and the 100-min sleep conditions was that 0-3-Hz wave amplitude increased significantly after the former, but not after the latter. In both studies, recovery sleep showed increased 0-3-Hz wave density. The neurophysiological implications of a response of EEG amplitude as opposed to wave density are briefly considered; separate measurement of these variables is more readily accomplished with period-amplitude than with spectral analysis. Our results further illustrate the importance of measuring sleep by physiological units, such as the successive NREMPs and REMPs. They also support other data that indicate that NREM-P1 plays a special role in human sleep: it responds selectively to sleep deprivation, shows the greatest ontogenetic variation across the human lifespan, and is the component of sleep that is most frequently abnormal in psychiatric patients. As we have long argued, it is inappropriate to conceptualize this high priority component of NREM sleep as "REM latency" and as a measure of REM "pressure" exclusively.

Comparison of technetium-99m MAG3 with iodine-131 hippuran by a simultaneous dual channel technique

Technetium-99m MAG3, a technetium-labeled analog of hippuran, was compared with [131I] hippuran using a simultaneous dual isotope study in 20 patients. The plasma clearance for MAG3 was lower than that of hippuran, but its plasma concentration was higher, resulting in similar rates of excretion and similar renal time-activity curves. Apart from better statistics with the technetium-labeled agent, there were no clinically significant differences in this group of patients.

Activity-dependent differences between rat fast and slow neuromuscular systems

Activity-dependent pharmacologic differences between the fast tibialis anterior and slow soleus neuromuscular systems of the rat were studied. The tibialis anterior was more sensitive than the soleus to d-tubocurarine tetanic fade (50 Hz), as determined from recordings of compound muscle action potentials. Pre-treatment with physostigmine prevented curare-induced tetanic fade in the tibialis anterior, but not the soleus. Additionally, when contractile tension was 80% blocked by d-tubocurarine, the tibialis anterior was more responsive than the soleus to the decurarizing action of tetanic stimulation (25, 50 and 100 Hz). These results disclose that activity-dependent pharmacologic differences exist between neuromuscular systems. Further, they indicate that the tibialis anterior and the soleus differ in their processes of transmitter release. It is speculated that differences in nerve terminal Ca2+ account for the observed pharmacologic differences between the tibialis anterior and soleus.

Drug delivery using vesicles targeted to the hepatic asialoglycoprotein receptor

We assessed the utility of liver-targeted vesicles as a drug delivery system for the treatment of liver diseases. Small, unilamellar vesicles (mean diameter, 60-80 nm) composed of dipalmitoylphosphatidylcholine, cholesterol, dipalmitoylphosphatidylglycerol and digalactosyldiacylglycerol (mol ratios, 40:40:5:15) are rapidly cleared from the blood in rats after intravenous injection. In vivo organ distribution shows that the liver is the major site of vesicle accumulation, with roughly 60-80% of the vesicle contents delivered to the liver. Isolated, perfused rat liver experiments show that the uptake is due to the hepatic asialoglycoprotein receptor, and the uptake process occurs with minimal vesicle leakage. At low doses of the vesicles, the single pass extraction by the liver is around 50%, which means that this vesicle formulation operates close to optimal efficiency as a drug delivery system to the liver. Binding of vesicles to the liver was determined to saturate at 6.5 mg total lipid/kg body weight, with a maximum steady-state turnover rate of vesicles at 37 degrees C of 79 micrograms lipid/min per kg body weight. This gives a receptor recycling time of around 80 min. We have incorporated this information into a pharmacokinetic model of vesicle distribution which quantitatively predicts the kinetics and dose dependence of vesicle uptake by the liver in vivo. This information can be used to optimize vesicle-mediated drug delivery to the liver.

Drug actions at mammalian motor nerve endings: the suppression of neostigmine-induced fasciculations by vecuronium and isoflurane

The occurrence of fasciculations following administration of agents is a well-known pharmacologic phenomenon. Using the cat soleus nerve-muscle preparation, intravenous neostigmine doses between 20-200 micrograms/kg evoked fasciculations in a dose-related manner. The data demonstrate that the fasciculations were the result of the direct effect of neostigmine acting at the motor nerve endings. Vecuronium in a dose-related manner (3 and 5 micrograms/kg iv) suppressed this prejunctional activity of neostigmine. The prejunctional effect of vecuronium explains its effectiveness in preventing succinylcholine-induced fasciculations. In the presence of isoflurane (end-tidal concentration 0.20-0.25%), the suppressant effect of vecuronium on motor nerve endings was enhanced. The prejunctional action of isoflurane may be a major contribution to the additive effects of non-depolarizing muscle relaxants and potent inhalation agents.

A note on shelf-life extension of British fresh sausage by vacuum packing

Vacuum packing of British fresh sausage in a low oxygen permeability film (Diolon) extended the product shelf-life at 6 degrees C to more than 20 d compared with 9-14 d in conventional packs. After 10 d storage, counts of key spoilage organisms such as yeasts and Brochothrix thermosphacta were generally 2 log cycles lower in vacuum packs. Vacuum-packed sausages also displayed a slower rate of loss of free sulphite. Variations in pack permeability to SO2 were not responsible for this. Losses of free SO2 in stored sausages are largely due to the production of sulphite-binding agents by yeasts. Selective enumeration of these yeasts showed them to be inhibited by conditions of vacuum packing. The extension of shelf-life observed is ascribed to the reduction in growth rate of the spoilage flora in vacuum packs coupled with the consequent maintenance of inhibitory levels of sulphite for a longer period.

Prejunctional effects of vecuronium in the cat

This study explored the prejunctional actions of vecuronium using the in vivo cat soleus nerve-muscle preparation. Vecuronium doses of 1 to 5 micrograms/kg iv suppressed the repetitive firing of the motor nerve endings, and the obligatory potentiation of the twitch response following high-frequency conditioning at 400 Hz for 10 s without attenuating neuromuscular transmission at 0.4 Hz. It was also found that extremely low doses of vecuronium had excitatory effects at the cat soleus motor nerve endings: doses of 0.5 and 1 microgram/kg iv evoked a modest postdrug repetitive firing of the nerve endings and a concomitant potentiation of the muscle responses. These dose-related agonist and antagonist activities suggest that at the motor nerve endings, vecuronium is a weak partial agonist. The major action of vecuronium at the motor nerve endings, however, was suppressive, and this antagonist action contributed to the neuromuscular blocking action of this muscle relaxant.

The potential for optimal (less than or equal to 2 cm) cytoreductive surgery in advanced ovarian carcinoma at a tertiary medical center: a prospective study

From November 1980 to April 1985, 50 consecutive previously untreated patients with FIGO Stage III and IV ovarian cancer were entered into a prospective trial to evaluate what percentage of such patients could have their tumors optimally cytoreduced (residual cancer less than or equal to 2 cm), what operation is required to achieve this goal, and what is the associated morbidity. Optimal cytoreduction was achieved in 76% of the 50 cases and in 77% of 18 cases referred as "inoperable." To achieve this goal, the six most common operations performed in descending order of frequency were bilateral salpingo-oophorectomy (100%), hysterectomy (98%), omental resection (86%), peritoneal tumor resection (40%), intestinal resection (36%), and gastrocolic ligament resection (16%). Fifty-eight percent of the patients had no major complications. The most significant complications were congestive heart failure in 4% and pulmonary embolus in 4%. Ninety-four percent of the patients had chemotherapy initiated in less than or equal to 14 postoperative days. It is concluded that approximately three-fourths of patients with advanced Stage III and IV ovarian carcinoma can have their tumors resected to less than or equal to 2 cm in greatest diameter. The value of such therapy on ultimate response to chemotherapy and survival will have to await longer follow-up, and will be the subject of a subsequent report.

Selection and optimisation of monoclonal antibodies for a two-site immunoradiometric assay for ACTH

Four monoclonal antibodies with predominant specificities towards different sequences within the ACTH molecule were investigated in a 2-site immunoradiometric assay (IRMA) for human ACTH. Antibody 3H9 recognises the extreme N-terminal sequence, antibodies 1A12 and 1D1 are specific for the mid N-terminal sequence but differ in that the former cross-reacts with alpha MSH whereas the latter does not, and antibody 2A3 recognises the C-terminal sequence. Combinations of iodinated antibodies with antibodies covalently linked to Sephacryl S300 were tested for their compatibility and potential for a sensitive assay. Two antibody combinations (1D1 plus 3H9 or 1A12) gave no dose-response curve indicating severe steric inhibition, whereas other combinations yielded assays with widely different detection limits (2-2400 ng ACTH/l). The combination of labelled 1D1 and solid-phase 2A3 gave the most sensitive assay and when optimised for antibody concentrations and incubation times the working range was 10-5 X 10(4) ng/l (CV less than 20%). The optimised sequential 2-step IRMA involves incubation of standard or test sample with labelled 1D1 for 18 h at 4 degrees C followed by incubation with solid-phase 2A3 for 2 h at room temperature, after which the labelled complex is separated by the sucrose layering technique. The detection limit of this IRMA was several 100-fold lower than by RIA using the same antibodies. The IRMA detected large molecular weight precursors containing the full ACTH sequence (22 000, 31 000 and 34 000) but not ACTH fragments (1-18, 1-24, 18-39). It is concluded that selected monoclonal antibodies provide a sensitive and rapid 2-site IRMA for intact ACTH and its precursors.

Pharmacologic excitability of rat motor nerve endings: the effect of adrenalectomy on neostigmine-induced fasciculations

Neostigmine-induced muscle fasciculations, quantitated as fasciculatory muscle action potentials, served as an indirect in vivo indicator of motor nerve ending (MNE) excitability. By this method, MNE excitability was depressed in adrenalectomized rats compared to matched intact controls. Daily or continuous administration of the mineralocorticoids aldosterone or desoxycorticosterone acetate restored MNE excitability toward normal; corticosterone, the endogenous corticosteroid having both mineralo- and glucocorticoid activity, was variably effective. There was a strong negative correlation (r = -0.95) between log plasma [K+]and the fasciculatory response to neostigmine. Dietary restriction of K in adrenalectomized rats lowered plasma [K+]to near normal and significantly increased MNE excitability. This effect of adrenalectomy on MNE excitability was further demonstrated by recording directly the neostigmine-induced repetitive neural discharges responsible for the muscle fasciculations. In adrenalectomized animals, neostigmine-induced neural discharges were reduced in intensity; restoration of neostigmine responsiveness was attained by lowering plasma [K+]through dietary restriction. Stimulus strength-duration relationships for both ventral and dorsal roots disclosed deficits in axonal excitability after adrenalectomy. These returned toward normal when plasma [K+]was lowered by K withdrawal from the diet. From these studies, it is concluded that 1) in adrenalectomized rats, peripheral nerve excitability, including the unmyelinated endings of motor nerve, is depressed; 2) mineralocorticoids play a significant role in restoring MNE excitability in these animals; 3) mineralocorticoid-induced changes in MNE excitability relate to the lowering of an elevated plasma [K+].

d-Tubocurarine sensitivities of a fast and a slow neuromuscular system of the rat

Fast and slow neuromuscular systems in the rat were compared with respect to their sensitivity to d-tubocurarine (dTC). The fast tibialis anterior was more sensitive than the slow soleus to dTC-induced block of contractile tension when stimulated at either 0.2 or 1.0 Hz. These results in the rat contrast those made by others in the cat. Thus, relative drug sensitivities are not simply related to neuromuscular type.

Prolongation of procaine's and procainamide's actions by binding to acryloyl polymers

Procaine and procainamide were covalently bound to acryloyl monomers and polymers. The dose-response and time-action parameters of the cardiac antiarrhythmic protection afforded by the prototype drugs and their acryloyl derivatives against chloroform-hypoxia-induced cardiac arrhythmias in unanesthetized mice and epinephrine-induced arrhythmias in alpha-chloralose anesthetized cats were determined. Similarly, the pharmacological parameters which characterized their acute toxic responses in unanesthetized male albino mice were also determined. The similar pharmacological spectra of their activity and the parallelism of their lethal dose-response curves indicate that the active constituents of the polymer derivatives are the local anesthetic moieties. Compared to the prototype drugs, the polymer derivatives were more potent on a molar basis and their pharmacological effects were prolonged. The increased potency and duration of action reinforce the idea that the local anesthetic moieties are pharmacologically active while still bound to the polymer backbones.

Methylprednisolone treatment of an organophosphorus-induced delayed neuropathy

Diisopropylfluorophosphate (DFP) injected into the femoral artery of cats causes a localized organophosphorus-induced delayed neuropathy (OPIDN). Gait disturbances develop in the treated leg 14 days after DFP exposure and reaches a maximum at 21 to 28 days after DFP. In vivo high-frequency conditioning of soleus motor nerve endings evokes stimulus-bound repetitive neural discharges (SBR) and an obligatory potentiation of the muscle contractile response (PTP). In this OPIDN model, SBR and PTP are maximally suppressed at 21 to 28 days after DFP. A high-dose regimen of methylprednisolone started 30 to 40 min after DFP exposure and lasting for 20 days prevented the development of OPIDN. In the methylprednisolone-DFP treated cats, SBR and PTP functions were not suppressed and not different from those in untreated normal cats.

Measurement of fasciculations as motor nerve ending discharges in the rat: a dose related effect of neostigmine

The muscle fasciculations caused by neostigmine and similar agents are the result of a primary drug action on motor nerve endings. Asynchronous, repetitive firing of action potentials are evoked at motor nerve endings which are then transmitted to muscle. A dose-response relationship between neostigmine dose and the rate of/or total neural activity has been established in the rat. This fasciculatory response to neostigmine can serve as an index of motor nerve ending excitability and may be useful in assessing the effects of certain pathological states or drug actions at the neuromuscular junction.

Disruption of written language in aphasia: a case study

This study documents the performance of a Wernicke aphasic on production of written discourse. The discourse data consisted of spontaneously produced texts of three different types: narrative discourse, personal and formal letters, and expository discourse. A detailed description of the language of this aphasic at a sentence and discourse level revealed preservation of discourse structure through proper use of cohesive devices despite severe disruption of linguistic structure at a sentence level.

Prejunctional and postjunctional effects of tubocurarine and pancuronium in man

The effects of small doses of tubocurarine and pancuronium on peak tetanic tension and tetanic maintenance were compared. Forty patients undergoing elective orthopaedic procedures under general anaesthesia were studied. Changes in neuromuscular transmission were measured by recording the isometric contraction of the adductor pollicis muscle evoked by supramaximal stimulation of the ulnar nerve at the wrist. Small doses of pancuronium affected predominantly the peak tetanic tension, while small doses of tubocurarine affected mainly tetanic maintenance. Thus, different degrees of depression of peak tetanic tension and tetanic maintenance were observed with tubocurarine and pancuronium. This clinical study supports Bowman's hypothesis, based upon laboratory findings in the cat, that prejunctional and postjunctional effects of neuromuscular blocking agents depend on their affinity for cholinoceptors at different sites.

An electrophysiologic and ultrastructural study of the phenylmethanesulfonyl fluoride protection against a delayed organophosphorus neuropathy

The delayed organophosphorus neuropathy caused by diisopropylfluorophosphate (DFP) can be prevented by pretreatment with phenylmethanesulfonyl fluoride (PMSF). A single injection of DFP (2 mg/kg) into a cat femoral artery produced a delayed neuropathy in the injected leg. Clinical neurotoxic signs in the DFP treated leg were most prominent at 21 to 28 days after DFP administration: a high-step gait with some tip-toe walking. During that time the capacity of the cat soleus alpha-motor nerve terminals to generate a stimulus-evoked repetitive discharge, known as SBR, was greatly attenuated. At that time, the ultrastructure of the motor nerve terminals demonstrated prominent alterations that correlated well with the motor nerve terminal SBR deficit. These alterations included the presence of extensive whorls in nerve terminals and axoplasms, the retraction and disruption of nerve terminals from the synaptic cleft, and a widening of secondary junctional folds. From the sampled population, the incidence of normal terminals in soleus muscles of the DFP-treated leg was only 2%. Cats which received PMSF (30 mg/kg ip) 24 hr before DFP administration did not develop any neurotoxic signs. Motor movements were normal. The SBR function of the soleus alpha-motor nerve terminals was not lost and its incidence approached normal values. Moreover, the ultrastructure was normal in 86% of examined neuromuscular junctions in the PMSF pretreated DFP cats. Thus, in this model, pretreatment with PMSF protected cats against the delayed neurotoxic effects of organophosphorus poisoning.

Beneficial action of glucocorticoid treatment on neuromuscular transmission during early motor nerve degeneration

The effects of a short-term, high-dose glucocorticoid pretreatment regimen (triamcinolone diacetate, 8 mg/kg i.m. daily for 7 days) were examined on neuromuscular transmission deficits observed in the in vivo cat soleus nerve-muscle preparation at 48 hr after soleus nerve transection. The pretreated preparations had 20% more functional motor nerve terminals than the untreated. This was evidenced by a significantly (P less than 0.01) lesser difference in the indirectly evoked isometric contractile tensions between the denervated muscle and the contralateral intact preparation as a result of prior glucocorticoid treatment. The glucocorticoid pretreatment also significantly improved the capacity of the trophically deprived soleus motor nerve terminals to maintain transmission during high-frequency activation (100 to 400 Hz for 10 s). Moreover, triamcinolone treatment before nerve transection completely prevented the development of an increased sensitivity to d-tubocurarine neuromuscular block in untreated, 48-h nerve-transected preparations. These results demonstrate an ability of an intensive high-dose glucocorticoid treatment to sustain single and repetitive neuromuscular transmission during early anterograde nerve degeneration.

A morphological study of the effect of glucocorticoid treatment on delayed organophosphorus neuropathy

The delayed neuropathy caused by the organophosphate diisopropylfluorophosphate (DFP) can be minimized by a high dose glucocorticoid regimen started after exposure to DFP. In cats 21 days after an intraarterial injection (2 mg/kg) of DFP, morphologic alterations of neuromuscular junctions and myelinated intramuscular axons are evident. These alterations include the presence of extensive lamellar whorls in nerve axons and terminals, the disruption and retraction of nerve terminals from the synaptic cleft and a widening of secondary junctional folds with coincident dispersion of the basal lamina. The pathologic changes while more intense in the DFP-treated leg are also evident in the contralateral leg. Only 2% of motor nerve terminals from the soleus of DFP-treated legs were rated as normal in morphologic evaluations. In contrast 90% were rated normal in cats exposed to DFP and subsequently treated with one dose of methyl prednisolone (90 mg/kg, i.v.) and 7 doses (8 mg/kg, i.m.) of triamcinolone over a 20 day period. The mechanism whereby glucocorticoid therapy exerted this effect during the time interval studied remains unresolved. However, this observation may be important in the further definition of both the normal and diseased state.

Hyperbaric medicine: state of the art, 1979

An attempt has been made to determine the clinical usage of hyperbaric oxygen therapy at 83 North American hyperbaric treatment centers from 1971 to 1978. Questions were asked about the conditions or diseases treated, yearly case load for each condition, location of functional hyperbaric chambers, types of chambers used, operating costs, and personnel requirements. Commercial diving chambers that treat decompression sickness and air embolism from diving accidents were included in the last two years of the survey. Fifty-seven responses were received; 30 treatment centers had multiple chambers, 24 had monoplace chambers, and three had both types of chambers. A total of 10,942 patients were treated during the eight-year survey period; 8,408 patients (76%) had category I or II conditions, as defined by the Undersea Medical Society. Of the 20 most commonly treated conditions, 17 were in category I or II. During the survey period, the use of hyperbaric oxygen increased, particularly in the treatment of decompression sickness, carbon monoxide poisoning, and osteomyelitis and osteoradionecrosis.

Correlation between anticurare activity of tetanic stimulation and neostigmine in anesthetized man

Frequency and dose-dependent changes in neuromuscular transmission were examined in 70 patients undergoing elective surgical procedures requiring the use of muscle relaxants. Anesthesia was induced with sodium thiopental and maintained with N2O-O2 and fractional dose of meperidine or fentanyl. Neuromuscular block was produced and maintained at 80% level with incremental intravenous doses of d-tubocurarine. Neuromuscular function was measured by recording the force of thumb adduction evoked by supramaximal stimulation of the ulnar nerve at the wrist. Single stimuli were applied every 2.5 seconds as square pulses of 0.1-msec duration. In 30 patients tetanic trains of 10-second duration ranging from 10 to 400 Hz were used. In 40 patients neostigmine doses ranging from 0.5 to 5.0 mg were used. Criteria for responses to 10-second tetanic trains during 80% neuromuscular block were determined and compared with responses after neostigmine. At a frequency of 50 Hz a complete tetanic fade was followed by partial posttetanic relief of block. At a frequency of 200 Hz tetanic fade was followed by complete but transient posttetanic decurarization. The original control twitch tension was not exceeded in posttetanic or postdrug responses. It is concluded that the transient after effects of tetanic stimulation are closely related to the anticurare effects of neostigmine.

The effects of phenylmethanesulfonyl fluoride on delayed organophosphorus neuropathy

A delayed localized neuropathy of peripheral nerves in a single hind leg of the cat develops after a single intraarterial 2 mg/kg injection of diisopropylfluorophosphate (DFP). This neuropathy is manifested by a maximum loss of the capacity of soleus alpha-motor nerve terminals to generate stimulus-bound repetition 21 days after DFP exposure. Phenylmethanesulfonyl fluoride (PMSF) is a protective inhibitor of the neurotoxic esterase which is associated with the development of the delayed organophosphorus neuropathy. Pretreatment of cats with PMSF (30 mg/kg i.p.) 24 h before the DFP injection protected the cats from the delayed neuropathy. No clinical neurotoxic signs were observed at 21 days after DFP. The stimulus-bound repetitive capacity of soleus alpha-motor nerve terminals was not lost at this time and its incidence was much greater than that which occurred in cats not pretreated with PMSF.

Muscle spindle function in organophosphorus neuropathy

The contribution of muscle spindle dysfunction to the neurological signs o-delayed organophosphorus neuropathy was investigated in the hindlimbs of cats intra-arterially injected with 2 mg/kg of diisopropylfluorophosphate (DFP). In this model of a delayed peripheral neuropathy, the animals exhibit a peculiar high-step gait and a sluggish response to noxious stimuli. These signs initially appear 14 days and are maximum 21--28 days after DFP administration. The position sensitivities of secondary but not primary soleus muscle spindles were depressed at 14 days after DFP. At 21 days after DFP, both primary and secondary endings had attenuated position sensitivities and significantly elevated thresholds. Spindle function was normal at 56 days after DFP exposure. The onset, peak and recovery of soleus muscle spindle dysfunction corresponded to those in alpha-motor axons, indicating the mixed sensory motor nature of organophosphorus neuropathy. Thus, impairment of both sensory and motor functions contributes to the neurological signs of this neuropathy.

A cardiac antiarrhythmic screening test in the rat: the effects of lidocaine, propranolol and quinidine

The dose-response and time-action parameters for the prototype antiarrhythmic drugs lidocaine, propranolol and quinidine were established using a cardiac antiarrhythmic screening procedure in the rat. This simple screening procedure produces severe cardiac arrhythmias, primarily ventricular fibrillation, in young post-weaning rats which have been pretreated with a single intramuscular injection of theophylline (20 mg/kg) 15 to 45 min prior to their inhalation of chloroform vapors.

Development of a cardiac antiarrhythmic screening test utilizing theophylline in the rat

Cardiac arrhythmias were produced in Sprague-Dawley-derived rats by chloroform challenge. The incidence of cardiac arrhythmias so induced increased with age and as a function of dose after pretreatment with theophylline. The dose-response and time-action parameters of theophylline's predisposing action to chloroform-hypoxia-induced cardiac arrhythmias were determined. This information has been utilized to develop a cardiac antiarrhythmic screening test in unanesthetized rats which is presented in the following paper.

A benzodiazepine-anticholinergic drug synergism in the prevention of stress-induced gastric mucosal erosion in mice

Chlordiazepoxide and clidinium each, as a function of dose, prevent stress-induced gastric mucosal erosion in mice. Clidinium was 2.5 times more potent than chlordiazepoxide. When used in a combination of 2 parts chlordiazepoxide and 1 part clidinium, the protective effect was nearly five times greater than that produced by clidinium alone. Furthermore, the combination dosing proved nearly three times more potent than the potency that was predicted from simple additivity of the individual drug effects. This potentiation appears related to the number of ways in which the combination treatment can decrease autonomic input to the gastric mucosa. Thus, the peripheral cholinergic blockade by clidinium may be potentiated by a central chlordiazepoxide suppression of both sympathetic and parasympathetic activities. Therefore, the combined use of these drugs in the therapy of stress-induced gastric disorder appears to have a rational pharmacologic basis.

The neuropathology of DFP at cat soleus neuromuscular junction

The fine structure of the cat soleus neuromuscular junction was studied following a single intra-arterial injection of di-isopropylfluorophosphate (DFP) into the right femoral artery. DFP induced separate subacute and delayed morphologic changes in soleus non-myelinated motor nerve terminals. Three days after DFP administration motor nerve terminals were reduced in number. Subacute DFP damage was also noted in the subneural apparatus and in the immediate subjacent muscle. Both pre- and post-junctional subacute changes were resolved two weeks post-DFP. One week following this initial regeneration, soleus motor nerve terminals underwent a delayed transient degeneration, followed by reinnervation of damaged endplates 6--8 weeks following DFP. Quantitative analysis of methylene blue-stained intramuscular nerves indicated that both subacutely and chronically denervated soleus muscle fibres were reinnervated by regeneration of the original motor axon. Reinnervation by means of collateral sprouting was insignificant. This mechanism of reinnervation and the rapidity with which it occurred suggests that both subacute and delayed soleus motor nerve damage is initiated from local actions of DFP on the non-myelinated terminal. The subacute reaction probably results from a direct cytotoxic action of DFP at pre- and post-junctional sites. The delayed nerve terminal degeneration may also stem from an acute effect not immediately detrimental to nerve function.

Motor nerve terminal defect following tenotomy

Post-tetanic potentiation and the underlying post-tetanic repetition in cat soleus muscle require normal motor nerve terminals. These indices of nerve terminal viability are depressed 10 days and absent 15 days after tenotomy of the soleus muscle.

The significance of hypotension developing during treadmill exercise testing

The significance of hypotension developing during treadmill exercise testing was evaluated and correlated with the findings at cardiac catheterization in two groups of patients. Twenty-five patients (Group I) had a fall in systolic pressure during exercise and were compared to 50 consecutive unselected patients (Group II) with a normal blood pressure response. Clinical characteristics were similar in both groups. Females comprised 48 per cent of the patients in Group I and only 30 per cent in Group II. The incidence of significant coronary artery disease was not different when the two groups were compared as a whole, 56 per cent in Group I and 36 per cent in Group II (P = NS). When males and females were considered separately, it was noted that the incidence of coronary artery disease was higher in hypotensive males (77 per cent) when compared to control males (40 per cent) (p less than 0.01). Females in both groups had a lower but comparable incidence of coronary artery disease (25 per cent and 27 per cent, respectively). Resting hemodynamics and angiographic characteristics, such as contraction abnormalities, and the number and distribution of diseased coronary vessels, were similar in both groups of patients. These findings suggest that hypotension in females does not necessarily connote coronary artery disease. Males with hypotension have a higher incidence of coronary artery disease, but the extent and distribution of their disease is no different from that of patients with a normal blood pressure response to exercise.

Attenuated dynamic responses of primary endings of muscle spindles: a basis for depressed tendon responses in acrylamide neuropathy

Depressed or lost tendon reflexes commonly observed in patients with peripheral neuropathies may result partly from attenuation of the dynamic discharge from the primary endings of muscle spindles. This possibility was investigated in cats with an experimental neuropathy induced with acrylamide (30 mg/kg/day intramuscularly). Achilles tendon reflexes and the dynamic discharge from primary muscle spindles were evaluated after five or ten injections of acrylamide. After five injections the animals were moderately impaired neurologically, the Achilles tendon reflex was difficult to elicit in 2 of 5 animals, and the dynamic responses of primary endings of soleus muscle spindles to stretch were depressed. Following ten injections of acrylamide the cats were severely impaired neurologically; tendon responses were either absent or difficult to elicit, and the dynamic responses of their muscle spindles to stretch were reduced by 50% (p less than 0.01). Additionally, the spindels responded to stretch with only 20 to 30% the normal number of afferent impulses. These data suggest that lost tendon responses in acrylamide neuropathy result in part from inadequate activation of motoneurons by spindle afferent discharge.

Position sensitivity of de-efferented muscle spindles in experimental acrylamide neuropathy

An experimental neuropathy was induced in cats by injections of acrylamide (7.5, 15 or 30 mg/kg/day) for 2 to 10 days. The responses of primary and secondary endings of soleus muscle spindles to stretch were evaluated and correlated with the appearance of ataxia and incoordinated motor movements. Animals that received 15 or 30 mg/kg/day became ataxic and demonstrated poor motor coordination on the 7th or 4th day, respectively. At these times, both primary and secondary endings of muscle spindles had elevated thresholds and diminished discharge frequencies. Continued acrylamide administration resulted in exacerbation of the clinical symptoms and further attenuation of spindle responses. The discontinuation of acrylamide was followed by slow recovery. Only those cats which received a total dose of 75 mg/kg or less remained asymptomatic and had normal spindle function. The coincidence of onset of motor coordination deficits and spindle dysfunction, coupled with a lack of demonstrable motor defect at the same time, suggests that the initial clinical features of acrylamide neuropathy may be partly the consequence of impaired spindle function.

Changes in the kinetics of muscle contraction in vitamin D-depleted rats

Using an in situ rat soleus neuromuscular preparation, changes in the muscle contraction kinetics in response to vitamine D depletion were studied. For a single isometric contraction, the time-to-peak tension (Tp) and the time-for-recovery-half-way-to-resting tension (T1/2r) were recorded. For a 150 Hz, 300 msec tetanus, the T1/2r was determined. Animals raised on high-calcium, high-phosphate, vitamin D-depleted diets showed prolongation of all parameters. Repletion of vitamin D returned Tp and T1/2r values to normal. Neither dietary calcium deficiency nor thyroparathyroidectomy produced an prolongation of Tp or T1/2r values. Therefore, based upon the experimental data, it appears that vitamin D or one of its metabolites, independent of any effect on the serum calcium or serum phosphate concentration, is necessary for normal muscle relaxation.

Glucocorticoid effects on the edrophonium responsiveness of normal and degenerating mammalian motor nerve terminals

An intensive short-term triamcinolone regimen in cats preserves the prejunctional actions of edrophonium in degenerating motor nerves. These edrophonium actions include the induction of a stimulus-dependent afterdischarge and the initiation of fasciculations. The relationship between fasciculations and stimulus-dependent afterdischarge is discussed. The glucocorticoid preservation of these edrophonium effects is like that previously reported for the preservation of posttetanic facilitation in motor nerves equally compromised. The results therefore show that glucocorticoid and facilitatory drug actions synergize to increase facilitation in degenerating but still functional motor nerves. This drug synergy is comparable to that which occurs in normal motor nerves. This interaction may provide a basis for effectively combining glucocorticoid and facilitatory drugs in the treatment of myasthenia gravis.

Effects of a single methylprednisolone dose on a facilitatory response of mammalian motor nerve

Long-term glucocorticoid dosing directly enhances a facilitatory function of cat soleus motor nerve terminals. Posttetanic potentiation (PTP) of soleus contraction is a manifestation of this prejunctional facilitation. The present study demonstrates that the same enhancement of facilitation is produced with a single large intravenous dose methylprednisolone. The single dosing method, however, showed an initial suppression of facilitation that neared recovery in four hours. Thereafter, the characteristic augmentation of prejunctional facilitation emerged, peaking in 24 hours. Return to control required four days. Knowledge of this time course enabled centrally disconnected motor nerve endings to be identified as the site of both phases of the steroid action. Since the neuromuscular facilitation studied is equivalent to that triggered by neostigmine-like drugs, the results infer that the antimyasthenic effect of glucocorticoids may involve a direct action on motor nerve endings.