Characterization of porphyrin interactions with peripheral type benzodiazepine receptors

We have examined organ and species variations in interactions of porphyrins with peripheral-type benzodiazepine receptors and explored structure-activity requirements for porphyrin-receptor interactions. Whereas potency of the benzodiazepine RO5-4864 varies several orders of magnitude in competing for receptors in different organs and species, effects of porphyrins and the isoquinoline carboxamide PK11195 are relatively constant. The structural requirements determining porphyrin affinity for benzodiazepine binding sites are fairly strict. The most potent porphyrins are those with prominent physiological functions.

Some exercises with the learned helpessness scale (lh/scale) in hindi

Learned Helplessness Scale - Hindi version (Dhar, Kohli & Dhar, 1987) was administered to 50 graduates. Scoring was done using the original method as given in the manual and by two of its variations. Correlations among the three forms of scoring were found to be very high (.85 and above). In another excercise, 30 of the subjects were administered P.G.I. Health Questionnaire N-2 and P.G.I. General Well Being Scales and in the third excercise 20 subjects were administered P.G.I. Health Questionnaire N-l and P.G.I. Locus of Control Scale, in addition to the L-H scale. The obtained correlations between LH and other variables show that it is positively correlated with neuroticism and negatively with the sense of general wellbeing, both correlations showing relationship of moderate degree only (about 25% overlap with the neuroticism and even lower for general well being). This feeling of learned helplessness was not related to the internal or external locus of control and the scale showed little effect of social desirability response set.

Trismus caused by paradoxical activity of jaw-closing muscles in brain stem tuberculoma

An ipsilateral trismus of jaw-closing muscles during jaw opening is reported in a patient with brain stem tuberculoma. This condition is only superficially simulated by spasticity or tetanus. The decisively differentiating clinical and electromyographic features and the possible pathophysiologic mechanism underlying such trismus are discussed.

Dermoid tumours occurring at the site of previous meningocele repair

Two cases of dermoid tumours following meningocele repair have been reported because of the rarity of the condition and paucity of literature. It should be stressed that a dermoid tumour should be considered in the differential diagnosis of neurological deterioration in patients with a repaired meningocele.

Monoclonal antibodies to human erythrocyte membrane Ca++-Mg++ adenosine triphosphatase pump recognize an epitope in the basolateral membrane of human kidney distal tubule cells

Human calcium transporting tissues were examined to determine whether they contained a protein similar to the Ca++-Mg++ adenosine triphosphatase (Ca++-Mg++ATPase) pump of the human erythrocyte membrane. Tissues were processed for immunoperoxidase staining using monoclonal antibodies against purified Ca++-Mg++ATPase. In human kidneys, specific staining was found only along the basolateral membrane of the distal convoluted tubules. Glomeruli and other segments of the nephron did not stain. Staining of erythrocytes in human spleen was readily observed. Human small intestine, human parathyroid, and human liver showed no antigens that crossreacted with the antibodies to Ca++-Mg++ATPase. Specific staining of distal tubule basolateral membranes from the kidney of a chimpanzee was also noted. Our experiments show, for the first time, that basolateral membranes of the human distal convoluted tubule contain a protein that is immunologically similar to the human erythrocyte Ca++-Mg++ATPase. These observations suggest that the cells of the distal convoluted tubules of human kidney may have a calcium pump similar to that of human erythrocyte membranes.

Trigeminal and peripheral neuropathy in a patient with systemic sclerosis and silicosis

The unusual occurrence of cranial (trigeminal) and peripheral neuropathy in a case of progressive systemic sclerosis (PSS) is described. The possible association of PSS with silicosis is also discussed.

The peripheral-type benzodiazepine receptor: a protein of mitochondrial outer membranes utilizing porphyrins as endogenous ligands

The peripheral-type benzodiazepine receptor is a site identified by its nanomolar affinity for [3H]diazepam, similar to the affinity of diazepam for the central-type benzodiazepine receptor in the brain. The peripheral-type benzodiazepine receptor occurs in many peripheral tissues but has discrete localizations as indicated by autoradiographic studies showing uniquely high densities of the receptors in the adrenal cortex and in Leydig cells of the testes. Subcellular localization studies reveal a selective association of the receptors with the outer membrane of mitochondria. Photoaffinity labeling of the mitochondrial receptor with [3H]flunitrazepam reveals two discrete labeled protein bands of 30 and 35 kDa, respectively. The 35-kDa band appears to be identical with the voltage-dependent anion channel protein porin. Fractionation of numerous peripheral tissues reveals a single principal endogenous ligand for the receptor, consisting of porphyrins, which display nanomolar affinity. Interactions of porphyrins with the mitochondrial receptor may clarify its physiological role and account for many pharmacological actions of benzodiazepines.

Disappearing CT lesions in epilepsy

A striking but reversible computed tomographic (CT) lesion corresponding to seizure activity is reported in a series of 46 epileptic patients. None of these patients had evidence of tuberculosis or cysticercosis, and all were treated with antiepileptic drugs only. Maximal radiological changes occurred in the area of maximal epileptic discharge; however, multiple lesions were seen in three cases. The CT lesion reappeared with recurrence of the ictus in four cases during follow-up, and this, too, disappeared after complete arrest of the seizures. The clinical, CT scan, and other investigatory findings suggest that the seizures may occasionally cause a CT-demonstrable focal abnormality, probably cerebral edema, a consequence of abnormal vascular permeability. Awareness of this radiological entity should avoid misdiagnosis of cerebral tumor, infarction or tuberculoma in patients with seizure disorder.

Reversible movement disorder in a patient with post traumatic basal ganglia haematoma

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Spontaneous intraventricular haemorrhage

Twenty-one patients with spontaneous intraventricular haemorrhage (IVH) were reviewed with particular reference to the clinical outcome. Based on clinical and computed tomography (CT) findings, as well as possible mechanisms governing the formation of IVH, we were able to identify two separate groups: patients with haemorrhage into ventricles without clinical or CT evidence of a lesion in adjacent brain parenchyma and patients with IVH occurring as a result of erosion of the ventricular wall by either a juxtaventricular small haematoma shown by CT and/or IVH with focal neurological deficit. Out of 12 patients in the first group, 8 survived and resumed their previous activities; in the second group (i.e. patients with clinical and/or CT evidence of adjacent intraparenchymal bleeding only three patients survived, two with considerable handicap. The overall prognosis, however, was significantly better in patients with IVH of unknown cause. Altered sensorium as an initial presentation was associated with a grave prognosis, irrespective of the cause of IVH. The outcome was not affected by the age of patient or the amount of blood within the ventricles. Our data suggest a favourable outcome in a relatively large percentage of patients with spontaneous IVH, if there is no clinical or CT evidence of concomitant parenchymal bleeding. Hence we question the notion that there is a grave prognosis in all kinds of IVH.

Porphyrins are endogenous ligands for the mitochondrial (peripheral-type) benzodiazepine receptor

"Peripheral-type" benzodiazepine receptors are localized to the outer mitochondrial membrane. We have identified potent competitive inhibitors of these receptors and purified them from human blood and from several rat organs. TLC analysis of the purified inhibitor from erythrocytes displays a single peak of inhibitory activity with an absorbance spectrum identical to hemin. All of the inhibitory activity in extracts of several tissues can be accounted for by their porphyrin and metalloporphyrin content. Pure hemin and protoporphyrin IX competitively inhibit mitochondrial benzodiazepine binding with Ki values of 41 and 15 nM, respectively, and are less active by a factor of 1000 at central-type benzodiazepine receptors. Thus, porphyrins appear to be endogenous ligands for mitochondrial benzodiazepine receptors.

Solubilization of an adenosine uptake site in brain

Procedures are described for the solubilization of adenosine uptake sites in guinea pig and rat brain tissue. Using [3H]nitrobenzylthioinosine [( 3H]NBI) the solubilized site is characterized both kinetically and pharmacologically. The binding is dependent on protein concentration and is saturable, reversible, specific, and high affinity in nature. The KD and Bmax of guinea pig extracts are 0.13 +/- 0.02 nM and 133 +/- 18 fmol/mg protein, respectively, with linear Scatchard plots obtained routinely. Similar kinetic parameters are observed in rat brain. Adenosine uptake inhibitors are the most potent inhibitors of [3H]NBI binding with the following order of potency, dilazep greater than hexobendine greater than dipyridamole. Adenosine receptor ligands are much less potent inhibitors of binding, and caffeine is without effect. The solubilized adenosine uptake site is, therefore, shown to have virtually identical properties to the native membrane site. The binding of the adenosine A1 receptor agonist [3H]cyclohexyladenosine [( 3H]CHA) to the solubilized brain extract was also studied and compared with that of [3H]NBI. In contrast to the [3H]NBI binding site [3H]CHA binds to two apparent populations of adenosine receptor, a high-affinity site with a KD of 0.32 +/- 0.06 nM and a Bmax of 105 +/- 30 fmol/mg protein and a lower-affinity site with a KD of 5.50 +/- 0.52 nM and Bmax of 300 +/- 55 fmol/mg protein. The pharmacology of the [3H]CHA binding site is consistent with that of the adenosine receptor and quite distinct from that of the uptake [( 3H]NBI binding) site. Therefore, we show that the adenosine uptake site can be solubilized and that it retains both its binding and pharmacologic properties in the solubilized state.

Nitrobenzylthioinosine binding in brain: an interspecies study

The binding of the potent adenosine uptake inhibitor [3H]nitrobenzylthioinosine ( [3H]NBI) to cerebral cortical membrane preparations from human, dog, guinea pig, rat, and mouse was investigated. Reversible, specific, saturable, high affinity binding was found in all five species with similar kinetic parameters. (Kd = 0.16-0.44 nM; Bmax = 128-196 fmol/mg prot.). Dilazep, hexobendine, and dipyridamole were all high potency inhibitors of [3H]NBI binding in human, dog, guinea pig and mouse preparations but not in rat. These compounds showed a competitive inhibition of [3H]NBI binding indicating that they are acting at the same site. Discrepancies seen in the rat appear to be a unique, species related anomaly. The dihydropyridine calcium antagonists also inhibited binding with lower potency than the adenosine uptake blockers. This inhibition was most potent in dog and human and suggests a relationship between the calcium channel and the adenosine uptake site.

Adenosine uptake sites in dog heart and brain; interaction with calcium antagonists

[3H] Nitrobenzylthioinosine (NBI) binding is characterized in dog heart and brain. Evidence is presented suggesting that [3H]NBI is binding to the adenosine uptake site in both tissues. Physiologic studies in open-chested dogs clearly demonstrate that NBI acts as a coronary vasodilator, consistent with an action at the adenosine uptake site. The binding is reversible, saturable and of high affinity (KD = 0.78 +/- .06 nM for heart and 0.52 +/- .05 nM for brain). Both dipyridamole and hexobendine are high potency inhibitors of [3H]NBI binding in heart and brain while other antihypertensives and vasodilators such as propranolol and nitroglycerin have no effect. The inhibition of [3H]NBI binding observed with dipyridamole was competitive indicating that both agents are acting at the same site. The dihydropyridine calcium antagonists also inhibited binding with a lower potency than the adenosine uptake blockers. Non-dihydropyridine calcium antagonists were much less potent in this regard. The inhibition of [3H]NBI binding observed with the dihydropyridine calcium antagonists was non-competitive suggesting that the calcium channel and adenosine uptake site may be coupled to each other.

Involvement of central nervous system in diabetes mellitus

Brainstem auditory evoked responses were recorded in 22 diabetic patients with a variable duration of illness (mean 5.8 years) and 14 normal healthy controls of comparable age. The initial 10 millisecond components, found to be most consistent and reproducible, were analysed. Variations in the form of individual wave latency, interpeak latencies and V wave amplitude were compared in both the groups. No difference was found in any of the parameters. It was concluded that central neural pathways are not involved at least initially in diabetes mellitus.

S-100-mediated inhibition of brain protein phosphorylation

The effects of the glial-specific, calcium-binding, S-100 protein on brain membrane and supernatant protein phosphorylation were assessed. S-100 concentrations as low as 5 micrograms/ml caused a marked inhibition of the phosphorylation of a soluble brain protein having a molecular weight of 73,000 daltons (73K). This protein was designated the S-100 protein-modulated phosphoprotein (SMP). Half-maximal inhibition of the phosphorylation of SMP by S-100 was obtained at concentrations of 12 micrograms/ml (0.57 microM). The inhibition of SMP phosphorylation by S-100 was calcium-dependent, with a calculated calcium Ka of 2.0 +/- 0.3 microM. SMP phosphorylation was also inhibited by calmodulin, but only partially and with a much lower potency. The inhibition of SMP phosphorylation by S-100 was not inhibited by fluphenazine, whereas the effect of calmodulin was. SMP was found in many brain areas, with the highest levels seen in the corpus callosum. Various peripheral tissues, such as kidney; liver; and pineal, pituitary, and adrenal glands, did not contain detectable SMP levels. At higher S-100 concentrations, greater than 10 micrograms/ml, the phosphorylation of several other soluble proteins was markedly inhibited. These proteins have molecular weights of 56K, 50K, and 47K. The phosphorylation of these proteins was enhanced by calmodulin. These data suggest that the S-100 protein may function to modulate the phosphorylation of brain proteins in a manner analogous to (although in a reciprocal fashion) that of calmodulin.

Hypertrichosis Universalis Congenita

A rare disease, hypertichosis universalis congenita was seen in a 7-month-old male child. Father also had a similar disorder. There was long black hair all over the body of the child except on the palms, soles and genitalia. Patient has been advised electrolysis when he is about 8 years of age. A brief review of literature in included.

Stapedius reflexometry. A diagnostic test of myasthenia gravis

Contraction of the stapedius muscle can be measured by electroacoustic impedance bridge. Muscle weakness and easy fatiguability which are cardinal features of myasthenia gravis (MG) are manifested by increased threshold and early decay of the stapedius reflex. This can be used as an objective test in the diagnosis of myasthenia gravis. Stapedius reflex was measured using Madsen Zo72 electroacoustic impedance bridge in 10 patients with myasthenia gravis and in an equal number of controls. The test was done before and 30 min after intramuscular injection of neostigmin. All patients with myasthenia gravis showed an elevated reflex threshold and 5 patients showed reflex decay. These findings reverted to normal after neostigmin injection. Stapedius reflexometry is a simple objective test for the diagnosis of myasthenia gravis.

Effect of transurethral resection on coagulation in carcinoma of prostate

Eleven patients with cancer of the prostate and 10 patients with benign prostatic hypertrophy (BPH) had thirteen parameters of coagulation evaluated before and after transurethral resection (TUR). Changes in fibrinogen and fibrin split products in both groups suggested potential incipient disseminated intravascular coagulation (DIC). It is concluded that prostatic cancer patients are no more susceptible to DIC than patients with BPH.