Serum and tear immunoglobulins in bacterial, fungal and viral corneal ulcers

Serum and tear IgA, IgG and IgM levels were studied in patients with bacterial, fungal and viral corneal ulcers. In patients with viral corneal ulcers serum IgA and IgG levels were found to be significantly raised, while IgM concentration remained unaltered. In bacterial and mycotic ulcerations, serum IgA, IgG and IgM levels remained unaltered. All three immunoglobulins were found to be raised in tears of patients with viral corneal ulcers, while only IgA levels were found to be increased in bacterial and mycotic ulcerations.

The effects of 5-HT1B characterizing agents in the mouse elevated plus-maze

Although the serotonergic system has been implicated in the modulation of anxiety states, the specific receptor subtypes that mediate these states require clarification. The effects of drugs that act preferentially at 5-HT1B receptors were evaluated on the behavior elicited in the elevated plus-maze, an animal model of anxiety. Variations in the intensity of light affected mouse behavior in the plus-maze; lower light intensity increased the entries to and time spent on the open arm in a manner similar to that seen with stress-attenuating circumstances. Opposite effects were observed in high light-intensity, similar to effects seen under elevated stress conditions. Chlordiazepoxide produced increased entries and time spent on the open arm, whereas pentylenetetrazol (PTZ) produced opposite effects. The preferential 5-HT1B agents TFMPP and mCPP exhibited a profile similar to PTZ. The effects of TFMPP in the plus-maze were reversed by chlordiazepoxide, but not by the benzodiazepine receptor antagonist flumazenil, which suggests that this effect is not directly mediated by benzodiazepine receptors. The decreased entries and time spent on the open arm of the maze following TFMPP or mCPP administration was possibly mediated by an antagonistic action at 5-HT1B receptors, since this effect was reversed by the selective 5-HT1B agonist CGS 12066B. The present study further demonstrates the utility of mouse behavior in the elevated plus-maze as a model for identifying anxio-modulatory substances.

Cholinergic modulation of aged-like retention deficits in young autoimmune mice

Separate age groups of autoimmune NZB/BINJ and non-autoimmune C57BL/BNNia mice were compared for habituation of locomotor activity and its retention over four separate testing sessions spaced at 24-hr intervals. A decline in locomotion (distance in cm) or in the time spent in the center zone as a function of sessions was taken to indicate retention for habituation to stimuli within the test apparatus. The time spent in the center zone decreased as a function of sessions in young and mature C57BL/6NNia mice but failed to show reliable between-session decreases in old (24-26-months) C57BL/6NNia mice. When compared with the old C57BL/6NNia mice, young NZB/BINJ mice showed similar impairments. Habituation of locomotion was present in all age groups of C57BL/6NNia mice, but absent in NZB/BINJ mice regardless of age. The retention impairments of 2-4 month old NZB/BINJ mice were attenuated when i.p. injections of 0.04-0.16 mg physostigmine/kg were given just following each habituation session. The effectiveness of physostigmine was substantially reduced when injections were delayed by 20 min or longer following each habituation session. The time-dependent reversal of the aged-like retention deficits by the cholinesterase inhibitor, physostigmine, suggests that cholinergic modulation of memory storage processes may be impaired in NZB/BINJ mice.

Animal models of drug withdrawal symptoms

There have been few attempts to model subjective symptoms of drug withdrawal using animals as subjects. Two approaches for developing such models are reviewed. First, using drug discrimination methodology, it may be possible to train animals to detect the effects of withdrawal. This method has two difficulties: 1) the only discriminations trained to date involve precipitated withdrawal, and 2) the stimulus controlling behavior is difficult to specify. Second, withdrawal from many drugs of abuse produces the symptom of anxiety, and it seems likely that animal models of anxiety could be useful for studying drug withdrawal. This hypothesis has been explored most fully using subjects trained to detect the discriminative stimulus properties of the putative anxiogenic drug pentylenetetrazole (PTZ). Withdrawal from benzodiazepines or ethanol substitutes fully for PTZ, and withdrawal from cocaine, morphine, and nicotine substitutes partially for PTZ. Emerging data suggest that other animal models of anxiety may also be useful for detecting drug withdrawal. The final portion of this review examines a behavioral test that is very sensitive for detecting physical signs of withdrawal in animals. In subjects maintained on an operant baseline using food as a reinforcer, withdrawal from a drug of dependence frequently is associated with disruption of that operant behavior. For example, tetrahydrocannabinol and cocaine, drugs that are not traditionally seen as having significant withdrawal signs, produce disruption of operant responding when high-dose administration is terminated, and their readministration reverses this behavioral disruption. Based on the observation that withdrawal is associated with anxiogenic stimuli, we suggest a method to determine if disruption of operant behavior may be related to these stimuli.

Effect of aspartate and glutamate on experimental myocardial infarction in rats

Cardiac necrosis was produced in rats by administering isoproterenol sulphate (85 mg/kg, sc for 4 days). The myocardial damage was proved by observing the elevated levels of serum aspartate amino-transferase, lactate dehydrogenase and creatine phosphokinase and the changes were confirmed by histopathology of the tissue. Both aspartate and glutamate (100 mg/kg, ip) significantly reduced the elevated levels of these enzymes. The average degree of cardiac necrosis produced in these rats when observed macroscopically and histologically was also found to be significantly reduced on pretreatment with aspartate and glutamate.

The pentylenetetrazol-like interoceptive stimulus produced by ethanol withdrawal is potentiated by bicuculline and picrotoxinin

We investigated whether the interoceptive discriminative stimulus (IDS) arising from ethanol withdrawal was related to decreased activity of the gamma-aminobutyric acid (GABA) system by determining whether the sensitivity of rats to the GABA antagonists was altered by chronic treatment with ethanol. Rats were trained to obtain food reward by responding on one lever following pentylenetetrazol (PTZ) and the other lever following saline. Whereas all of the trained rats selected the PTZ-appropriate lever after PTZ, no more than 50% of them selected this lever following an optimum dose of bicuculline or picrotoxinin. After either saline or diazepam (5 mg/kg), all of the rats selected the saline-appropriate lever. Ethanol (0.24 mol/kg/day) was then administered to the rats for 4 days via a nutritionally balanced liquid diet. Between 48 and 96 hours postethanol, 30% of the rats selected the PTZ-appropriate lever following saline, whereas selection of this lever was increased to 80% following either bicuculline or picrotoxinin. Thus, further antagonism of GABAergic activity increased the subjective effect of ethanol withdrawal. These data support the hypothesis that the PTZ-like IDS produced during withdrawal from ethanol is related to an ethanol-induced deficit in the activity of the GABA-benzodiazepine receptor-coupled chloride channel.

Serum enzymes in head and neck cancer. IV: 5-nucleotidase

Serum 5-nucleotidase levels have been estimated in a group of 50 patients with head and neck cancer. The mean value was significantly higher in patients compared to the controls. In patients with non-malignant growths, the activity was comparable with the controls. The increase was higher in patients with proliferative lesions than those with ulcerative growths. Enzyme activity was found to be increased with the advancement in the stage of cancer. The rise was comparatively higher in patients with cervical metastasis. After radiotherapy, a gradual and significant reduction of serum 5-nucleotidase activity was observed.

Effect of vitamin D administration during pregnancy on neonatal growth in the rat

Groups of rats on commercial diet were injected 3,000 IU (group 2) and 7,500 IU (group 3) of vitamin D3 on the 10th day of pregnancy. Compared to control pups (group 1), the pups in group 2 and 3 weighed significantly more on the 10th, 20th and 28th day of age. At 28th day of age, study of the gastrocnemius muscle revealed significantly greater organ weight, protein, DNA and RNA contents, protein/DNA and RNA/DNA ratios in group 2 and 3 pups than in controls. In the liver, whereas all these indices were significantly increased in group 3 pups, only protein/DNA and RNA/DNA ratios were significantly increased in group 2 pups. Brain weight, its RNA content and RNA/DNA ratio were significantly greater in group 2 and 3 pups than in controls. The results suggest that vitamin D administration in pregnancy promotes soft tissue growth in the pups by enhancing cellular proliferation and hypertrophy.

Sensitivity of pentylenetetrazol discrimination increased by a stimulus fading technique

The interoceptive stimulus produced by pentylenetetrazol (PTZ) is pharmacologically similar to anxiety and is used in a behavioral assay for anxiety-related stimuli (the PTZ model of anxiety). The stimulus fading technique was tested as a method to increase the sensitivity of this assay. Rats were trained with food-reward to press one lever after injection of PTZ and an alternate lever after saline. Rats initially learned the discrimination at a PTZ dose of 20 mg/kg. They were then trained with sequentially lower doses until they reliably discriminated a PTZ dose of 10 mg/kg. Substitution tests with other doses and drugs showed that, after the fading procedure, dose-response curves were shifted to lower doses for PTZ, Ro 5-3663, and nicotine Similarly, the dose of diazepam required to block the low dose of PTZ was lower than that required to block the higher dose of PTZ. These results indicated that the sensitivity of the discrimination was enhanced in rats trained to discriminate a lower dose of PTZ. Doses of nikethamide, cocaine, and yohimbine that did not substitute for the higher dose of PTZ also did not substitute for the lower dose. These data suggest that rats can be trained to discriminate a low dose of PTZ by the stimulus fading technique. Moreover, they suggest that this training method does not compromise the specificity of the discrimination.

Characterization of a pentylenetetrazol-like interoceptive stimulus produced by ethanol withdrawal

Rats were trained with food reinforcement to discriminate the anxiogenic drug pentylenetetrazol (PTZ, 20 mg/kg) from saline in a two-lever-choice task. In Experiment 1, ethanol, 8.25% w/v was given by gavage (7/day) for 4 days, with doses titrated to maintain moderate intoxication. After termination of ethanol, the rats exhibited mild overt signs of withdrawal and, in discrimination tests with saline as the test substance, they selected the PTZ lever, an effect reversed by ethanol, 2 g/kg, and by diazepam, 5 mg/kg. In Experiment 2, rats drank a nutritionally complete liquid diet containing ethanol, 4.5% w/v, for 1 week. They became tolerant to the intoxicating effect of ethanol, and blood ethanol concentration mounted with continued dosing. On termination of chronic ethanol, rats selected the PTZ lever before the onset of overt physical signs of withdrawal, and both measures returned to base line within 3 days. In Experiment 3 the percentage of rats selecting the PTZ lever after termination of ethanol depended upon the dose (up to 12.5 g/kg) and duration (up to a ceiling effect by 3 days) of ethanol administered chronically. These results indicate that a PTZ-like stimulus produced interoceptively can be demonstrated in the rat as an objective measure of ethanol withdrawal. This paradigm may provide insight into the symptom of anxiety associated with ethanol withdrawal.

CGS 8216, a benzodiazepine receptor antagonist, enhances learning and memory in mice

Mice pretreated with the benzodiazepine antagonist, CGS 8216 (2.5, 10, or 40 mg/kg, i.p.) learned a T-maze discrimination to a fixed performance criterion more rapidly than vehicle-treated mice. In retention tests conducted one week later, the drug-treated groups had better first-trial recall and greater difficulty reversing the previously trained maze habit when compared with controls, suggesting improved memory for the previously trained maze habit. The enhanced acquisition and retention following CGS 8216 was similar to that observed previously with another benzodiazepine antagonist, flumazenil (Ro 15-1788). It is postulated that CGS 8216 and flumazenil could act at benzodiazepine receptors to antagonize a tonic inhibitory influence of endogenous, diazepam-like, benzodiazepine receptor ligands on memory processes.

Autoimmunity and age-associated cognitive decline

It is suggested that the immune system may play a role in the etiology of age-associated cognitive decline and/or Alzheimer's disease. The relationship between brain-reactive antibodies (BRA) and age-associated cognitive dysfunction is reviewed and discussed. A parallel relationship between BRA increases with age and decline of avoidance learning capacity is described in mouse models. Transfer of immunity from old to young mice was found to accelerate both age-related formation of brain-reactive antibodies and age-related decline of avoidance learning capacity. Short-lived mouse genotypes with accelerated autoimmunity were found to show accelerated age-related declines in their ability to acquire an avoidance response when compared with nonautoimmune mice. Overall, these findings suggest that the immune system could be an important target for development of intervention strategies aimed at extending the intellectually competent period of life. Mice in which autoimmunity is accelerated may be useful as models for the development of such interventions.

Enhancement of learning and memory in mice by a benzodiazepine antagonist

Benzodiazepines, a class of drugs widely employed as anxiolytics and anticonvulsants, can induce impairments of learning and memory. The purpose of the present investigation was to determine if a benzodiazepine receptor antagonist, flumazenil (Ro 15-1788), could enhance learning and memory. Pretraining injection of flumazenil (2.5 to 40.0 mg/kg) was found to enhance both learning and memory in a test requiring young mice to discriminate the correct arm of a T-maze to escape mild electric shock. In a second test, which required mice to passively avoid a dark chamber after shock, flumazenil pretreatment prevented the occurrence of amnesia induced by the cholinergic receptor antagonist scopolamine. It is hypothesized that flumazenil may facilitate learning or memory processes by reversing a negative modulatory influence of endogenous diazepam-like ligands for benzodiazepine receptors.

Serum immunoglobulin E levels in patients with head and neck cancer

Serum immunoglobulin E levels were estimated in 50 patients with head and neck cancer and in 25 controls. Mean serum IgE value was significantly higher in patients with various sites of cancer in the head and neck region other than carcinoma of the tonsil. The levels increased with advancement in the stage of cancer. There was, however, no difference in mean serum IgE value with respect to the character of the lesion, to the histopathological type of growth or to radiotherapy. In patients with carcinoma of the tonsil, the mean serum IgE concentration was significantly lowered.

Effect of acute environmental heat stress on urinary water and electrolyte excretion in the rat

Plasma cortisol and urinary excretion of water, sodium, potassium, calcium and magnesium have been studied in the rat after application of heat stress. There was a significant increase in plasma cortisol level after exposure to heat. During heat stress complete cessation of urine formation was observed. In the next 30 min there was statistically significant increase in the urinary excretion of water, sodium and calcium but not of potassium and magnesium. Urinary calcium/magnesium ratio was also significantly elevated. The increase in urinary water and electrolyte excretion seemed to be mediated through prostaglandins since it could be abolished by administration of indomethacin prior to the application of heat stress. On the basis of these results, the possible role of heat stress in the genesis of urolithiasis has been discussed.

Withdrawal from diazepam substitutes for the discriminative stimulus properties of pentylenetetrazol

Rats were trained to discriminate pentylenetetrazol (PTZ, an anxiogenic drug), 20.0 mg/kg, from saline using a food-maintained two-lever-choice task. When treated chronically with diazepam (DZP) and tested with the benzodiazepine-receptor antagonist Ro 15-1788, withdrawal from DZP produced a PTZ-like stimulus in these subjects that was related directly to the dose of DZP given every 8 hr for 6 days. In contrast, only the highest dose of DZP (80 mg/kg/8 hr) given chronically produced even minimal physical signs of precipitated abstinence after Ro 15-1788. In a separate experiment, Ro 15-1788 produced a PTZ-like stimulus when given at 2-day intervals during chronic administration of DZP. In this experiment, rats were maintained on DZP, 40.0 mg/kg/6 hr for 14 days. These subjects were tested with Ro 15-1788, 40.0 mg/kg, every 2 days during days 6 through 14 of chronic DZP, and Ro 15-1788 substituted for PTZ on 4 of these 5 tests. Because these experiments involved periods of nontraining on the discrimination task, a final experiment was performed to test the stability of stimulus control in rats trained to detect PTZ. DZP was administered for up to 20 days, withdrawal was precipitated by Ro 15-1788 and after an additional 16 to 40 days of nontraining, stimulus control was tested. There was no significant decline in stimulus control over this period. These results suggest that PTZ discrimination provides a sensitive, stable assay for the detection of withdrawal from benzodiazepine dependence.

Age differences in acquisition and retention of one-way avoidance learning in C57BL/6NNia and autoimmune mice

Acquisition and 48-h retention of a step-up active avoidance response were studied in separate age groups of C57BL/6NNia mice (aged 1.5, 3.5, 6, 12, or 26 months) and five strains of genetically autoimmune mice differing in life span. The C57BL/6NNia mice showed no change in ability to acquire the avoidance response between 1.5 and 3.5 months, but showed a steady decline in that ability thereafter. Mouse strains with early-onset autoimmune disorder (NZB/B1NJ, MRL/MpJ-lpr, and BXSB/MpJ) showed declines in acquisition capability between 1.5 and 3.5 months of age, whereas mouse strains with mild, late-onset autoimmune disorder (MRL/MpJ- + and NZBWF1/J) showed stable or improved acquisition during that period. Both the C57BL/6NNia and NZB/B1NJ mice showed age-dependent declines in 48-h retention performance by 12 months of age. These findings suggested that while 48-h retention performance deficits were most related to chronological age, avoidance acquisition deficits were related to development of autoimmunity.

Adenosine deaminase activity in leprosy (a preliminary study)

Adenosine deaminase (ADA) activity was studied in 25 patients having different types of leprosy and 25 healthy volunteer as control. There was definite rise of ADA activity in BL (72.9 +/- 6.85), LL (56.7 +/- 3.35) and BT (39.1 +/- 8.28) which was statistically significant when compared to ADA activity in healthy control (9.7 +/- 0.53).

Quantal detection and homogeneous sensitivity in a pentylenetetrazol discrimination

Rats were trained to discriminate pentylenetetrazol (PTZ, 20 mg/kg) from saline in a two-lever operant task. Correct lever presses were reinforced with food under the control of a fixed ratio 10 schedule. In tests of the effect of PTZ dose on lever selection, rats selected the PTZ lever in a dose-dependent manner, with peak latency at the approximate ED50 dose (10 mg/kg). Rats usually pressed only the selected lever, regardless of dose, indicating that lever selection was a quantal (or bimodal) function of stimulus intensity. Lever biases observed during training sessions did not predict the performance of individual rats in tests with the ED50 dose. In three independent trials with this intermediate dosage, the rats selecting the PTZ lever varied from trial to trial, suggesting that rats detecting this dose did not form a stable subgroup. The pattern of lever selections across these three trials was not significantly different from that predicted by a model in which all subjects shared the same probability for detecting the drug stimulus. These results demonstrate that lever selection in a two-lever drug-discrimination task can be quantal in nature, and suggest that rats trained with PTZ, 20 mg/kg, are homogeneous in sensitivity to this stimulus.

Effect of dietary restriction with and without leucine supplementation on hepatic protein status in rats

In the present study effect of dietary restriction with and without leucine supplementation was observed on body and liver weights, and liver protein status, in adult rats. Animals were fed on two diets ad lib or were on 50 per cent and 25 per cent intakes. Dietary restriction resulted in loss of body and liver weights, hepatic protein, free-alpha-amino nitrogen and RNA contents and liver cell size (liver weight/DNA ratio). When compared with the control group, the decrease in these parameters was more in the dietary restricted leucine supplemented group. However, hepatic DNA content was not changed with the change in dietary regimen. The results suggest that leucine supplementation with dietary restriction may be more harmful for the animal than dietary restriction alone.

Enhancement of a diazepam withdrawal symptom by bicuculline and yohimbine

The role of the GABA system in producing a pentylenetetrazol-like interoceptive discriminative stimulus during withdrawal from diazepam was investigated in rats by determining the sensitivity of this system to GABAergic drugs before and after chronic treatment with diazepam. Food-restricted rats were trained to obtain a reward of food by responding on one lever following an injection of pentylenetetrazol (PTZ; 20 mg/kg) and the other lever following an injection of saline (1 ml/kg). After rats had acquired this discrimination, the effectiveness of Ro 15-1788, bicuculline and yohimbine to substitute for pentylenetetrazol was determined. Prior to chronic treatment with diazepam, rats selected the appropriate lever for saline after Ro 15-1788 and the appropriate lever for pentylenetetrazol after bicuculline (0.04-2.5 mg/kg) or yohimbine (0.16-5.0 mg/kg). Although the selection of the appropriate lever for pentylenetetrazol was dose-dependent, full substitution for pentylenetetrazol was not obtained with either drug as larger doses of bicuculline produced convulsions while the rats began to select the appropriate lever for saline after larger doses of yohimbine (bell-shaped curve). Diazepam blocked the pentylenetetrazol-like interoceptive discriminative stimulus for bicuculline. The rats were then injected with diazepam (80 mg/kg/8 hr) for 24 days. Upon termination of the administration of diazepam, the animals were tested for lever-selection following the administration of saline, Ro 15-1788 (10 mg/kg), bicuculline (0.32, 0.64 and 1.25 mg/kg) or yohimbine (0.16, 0.64 and 2.5 mg/kg). After saline, 33% of the rats selected the appropriate lever for pentylenetetrazol whereas selection of this lever was enhanced after Ro 15-1788, bicuculline or yohimbine.(ABSTRACT TRUNCATED AT 250 WORDS)

Modulation of the discriminative stimulus produced by pentylenetetrazol by centrally administered drugs

Pentylenetetrazol is anxiogenic in humans and produces an interoceptive discriminative stimulus in rats which is mimicked by anxiogenic drugs and other treatments and antagonized by anxiolytic drugs. It was proposed that the discriminative stimulus of pentylenetetrazol originates centrally. This hypothesis was tested by injecting small amounts of anxiogenic or anxiolytic drugs into the brain and comparing their ability to mimic or block, respectively, the response to pentylenetetrazol, observed after systemic injection. Food-restricted rats were trained in a two-lever operant task to discriminate the interoceptive discriminative stimulus produced by pentylenetetrazol. Intraperitoneal or intracerebroventricular injection of Ro 5-3663 was substituted in a dose-dependent manner for the stimulus produced by systemically administered pentylenetetrazol. Diazepam injected systemically, blocked the pentylenetetrazol-like stimulus associated with Ro 5-3663 administered systemically or centrally. Midazolam injected intracerebroventricularly and in a dose-dependent manner, antagonized the discriminative stimulus produced by systemic injection of pentylenetetrazol. When injected into the amygdala, midazolam also antagonized in a dose-dependent manner the pentylenetetrazol-induced stimulus. Thus, these data suggest that there are sites in the CNS for both the initiation of a pentylenetetrazol-like stimulus by Ro 5-3663 and the antagonism of the stimulus produced by pentylenetetrazol by midazolam.