Oral delivery system of insulin microspheres: effect on relative hypoglycemia of diabetic albino rats

The aim of the present work was to investigate the effectiveness of a dosage form approach for monitoring both the inactivation and the absorption process by targeting insulin delivery to the upper region of small intestine. The dosage form is based on the incorporation of insulin with protease inhibitor and absorption enhancer into polyacrylic polymer Eudragit L-100. Insulin microspheres were prepared by solvent evaporation technique. And also study the effect of these microspheres upon the relative hypoglycemia (RH) effect in white diabetic albino rats has been studied in comparison to that produced after subcutaneous injection of bovine insulin solution. The oral administration of formulation with aprotinin and bile salts gave significant (p< 0.01) hypoglycemia when compared with formulation with insulin alone and with insulin and bile salts. However, the duration, course and the intensity of effect were different for each formulation. It was interesting to observe that the co-administration of aprotinin and bile salts produce prolonged and significant reduction of blood glucose level. A reduction of 4.47-36.81% in plasma glucose levels and RH of about 11.7% relative to subcutaneous injection of soluble insulin solution can be achieved by encapsulation along with protease inhibitor and bile salts.

High-frequency, depressing inhibition facilitates synchronization in globally inhibitory networks

Motivated by the study of sharp wave-associated ripples, high-frequency (approximately 200 Hz) extracellular field oscillations observed in the CA1 region of the rat hippocampus during slow-wave sleep and periods of behavioural immobility, we consider a single inhibitory neuron synapsing onto a network of uncoupled, excitatory neurons. The inhibitory synapse is depressing and has a small synaptic delay. Each excitatory cell provides instantaneous, positive feedback to the inhibitory cell. We show that the interneuron can rapidly synchronize the action potentials of the pyramidal cells if the frequency of inhibitory input is increased in a ramp-like manner as occurs during the ripple. We show that the basin of attraction of the synchronous solution is larger when the inhibition frequency is gradually increased as opposed to remaining constant.

Intussusception in southern Indian children: lack of association with diarrheal disease and oral polio vaccine immunization

BACKGROUND

Intussusception is the most common cause of intestinal obstruction in young children and has been reported as a complication of a recently withdrawn tetravalent reassortant rotavirus vaccine.

METHODS

We studied the history, clinical presentation, management and outcome of intussusception presenting to a tertiary care hospital in southern India over a 10-year period, in order to assess potential association with diarrheal disease and immunization.

RESULTS

Data from 137 index cases and 280 control subjects indicated that the risk of diarrheal disease or oral polio vaccine administration in the month prior to presentation was similar in the index cases and controls. Mean time to presentation to hospital after developing symptoms was 1.8 days, and 77.3% of patients required surgery, with 47.4% undergoing intestinal resection. Mortality was 0.006%.

CONCLUSIONS

No association could be demonstrated between gastroenteritis or oral poliovirus vaccine immunization and intussusception in southern Indian children. These children presented later and required operative intervention more frequently than has been reported in other studies, but had a good outcome with low mortality.

Phase precession and phase-locking of hippocampal pyramidal cells

We propose that the activity patterns of CA3 hippocampal pyramidal cells in freely running rats can be described as a temporal phenomenon, where the timing of bursts is modulated by the animal's running speed. With this hypothesis, we explain why pyramidal cells fire in specific spatial locations, and how place cells phase-precess with respect to the EEG theta rhythm for rats running on linear tracks. We are also able to explain why wheel cells phase-lock with respect to the theta rhythm for rats running in a wheel. Using biophysically minimal models of neurons, we show how the same network of neurons displays these activity patterns. The different rhythms are the result of inhibition being used in different ways by the system. The inhibition is produced by anatomically and physiologically diverse types of interneurons, whose role in controlling the firing patterns of hippocampal cells we analyze. Each firing pattern is characterized by a different set of functional relationships between network elements. Our analysis suggests a way to understand these functional relationships and transitions between them.

Could a herpesvirus be the cause of Kawasaki disease?

Kawasaki disease (KD) is an acute vasculitis of early childhood, the cause of which remains unknown. Many lines of evidence suggest an infectious aetiology, which may-in association with host genetic factors-lead to the characteristic clinical presentation of this disease. Accumulating data including animal models and epidemiological and immunological studies, suggest that viruses have an important role in human vasculitic disease. Whereas many infectious agents including viruses have been postulated as possible causes of KD, no single agent has been shown definitely to be associated with this disease and the causative agent remains elusive. We hypothesise that a ubiquitous virus of the gamma herpesvirus family is the likely aetiological agent for KD in genetically susceptible individuals.

Kawasaki disease: an evidence based approach to diagnosis, treatment, and proposals for future research

This article proposes a clinical guideline for the diagnosis and treatment of Kawasaki disease in the UK based on the best available evidence to date, and highlights areas of practice where evidence is anecdotal or based on retrospective data. Future research as proposed by the London Kawasaki Disease Research Group is outlined, and clinicians are invited to prospectively enroll their suspected cases into this collaborative research project.

PYK2 as a mediator of endothelin-1/G alpha 11 signaling to GLUT4 glucose transporters

Endothelin-1 (ET-1) signaling through G alpha(q/11) stimulates translocation of intracellular GLUT4 glucose transporters to the plasma membrane of 3T3-L1 adipocytes by an unknown mechanism that requires protein tyrosine phosphorylation and ADP-ribosylation factor 6 (ARF6) but is independent of phosphatidylinositol 3 (PI3)-kinase. In contrast, insulin action on this process requires PI3-kinase but not ARF6. Here we report the identification of two proteins selectively tyrosine-phosphorylated in response to ET-1 but not insulin: the Ca(2+)-activated tyrosine kinase PYK2 and its physiological substrate, the adhesion scaffold protein paxillin. Endogenous paxillin as well as expressed Myc-tagged PYK2 or a Myc-tagged kinase-deficient PYK2 protein were acutely directed to F-actin-rich adhesion sites from the adipocyte cytoplasm in response to ET-1 but not insulin. CADTK-related non-kinase (CRNK) is a dominant negative form of PYK2 containing the C-terminal portion of the protein, which binds paxillin but lacks the PYK2 autophosphorylation site (Tyr(402)). CRNK expression in 3T3-L1 adipocytes inhibited ET-1-mediated F-actin polymerization and translocation of Myc-tagged GLUT4-enhanced green fluorescent protein (EGFP) to the plasma membrane without disrupting insulin action on these processes. These data reveal the tyrosine kinase PYK2 as a required signaling element in the regulation of GLUT4 recycling in 3T3-L1 adipocytes by ET-1, whereas insulin signaling is directed through a different pathway.

G(alpha)11 signaling through ARF6 regulates F-actin mobilization and GLUT4 glucose transporter translocation to the plasma membrane

The action of insulin to recruit the intracellular GLUT4 glucose transporter to the plasma membrane of 3T3-L1 adipocytes is mimicked by endothelin 1, which signals through trimeric G(alpha)q or G(alpha)11 proteins. Here we report that murine G(alpha)11 is most abundant in fat and that expression of the constitutively active form of G(alpha)11 [G(alpha)11(Q209L)] in 3T3-L1 adipocytes causes recruitment of GLUT4 to the plasma membrane and stimulation of 2-deoxyglucose uptake. In contrast to the action of insulin on GLUT4, the effects of endothelin 1 and G(alpha)11 were not inhibited by the phosphatidylinositol 3-kinase inhibitor wortmannin at 100 nM. Signaling by insulin, endothelin 1, or G(alpha)11(Q209L) also mobilized cortical F-actin in cultured adipocytes. Importantly, GLUT4 translocation caused by all three agents was blocked upon disassembly of F-actin by latrunculin B, suggesting that the F-actin polymerization caused by these agents may be required for their effects on GLUT4. Remarkably, expression of a dominant inhibitory form of the actin-regulatory GTPase ARF6 [ARF6(T27N)] in cultured adipocytes selectively inhibited both F-actin formation and GLUT4 translocation in response to endothelin 1 but not insulin. These data indicate that ARF6 is a required downstream element in endothelin 1 signaling through G(alpha)11 to regulate cortical actin and GLUT4 translocation in cultured adipocytes, while insulin action involves different signaling pathways.

Neural mechanisms for generating rate and temporal codes in model CA3 pyramidal cells

The effect of synaptic inhibition on burst firing of a two-compartment model of a CA3 pyramidal cell is considered. We show that, depending on its timing, a short dose of fast decaying synaptic inhibition can either delay or advance the timing of firing of subsequent bursts. Moreover, increasing the strength of the inhibitory input is shown to modulate the burst profile from a full complex burst, to a burst with multiple spikes, to single spikes. We additionally show how slowly decaying inhibitory input can be used to synchronize a network of pyramidal cells. Implications for the phase precession phenomenon of hippocampal place cells and for the generation of temporal and rate codes are discussed.

Role of destructive operations in modern day obstetrics

One hundred and forty-one cases of obstructed labour was referred to RG Kar Medical College and Hospital in the last one year. Out of 12,034 total hospital deliveries, incidence of obstructed labour was 1.17% whereas 36 cases (0.29%) accounted for intra-uterine foetal death (IUD). Of the IUD with obstructed labour, 69.4% were delivered by destructive operation and 30.6% by lower segment caesarean section (LSCS). Craniotomy was performed in 44.4% cases and evisceration in 25% of cases. About 68% of the patients were in the young age group belonging to 20-30 years and 36% of cases were primigravida. It ws found that cephalopelvic disproportion was the commonest cause of obstruction for which craniotomy was performed. Traumatic rupture uterus was encountered in one case. There was no maternal death following destructive operation.

Role of synaptic delay in organizing the behavior of networks of self-inhibiting neurons

We consider a pair of mutually coupled inhibitory neurons in which each neuron is also self-inhibitory. We show that the size of the synaptic delay determines the existence and stability of solutions. For small delays, there is no synchronous solution, but a stable antiphase and a stable on-state solution. For long delays, only the synchronous solution is stable. For intermediate delays, either the antiphase or synchronous solutions are stable. In contrast to prior work, for stability of synchrony, we only require the existence of a single slow process.

A temporal mechanism for generating the phase precession of hippocampal place cells

The phase relationship between the activity of hippocampal place cells and the hippocampal theta rhythm systematically processes as the animal runs through the region in an environment called the place field of the cell. We present a minimal biophysical model of the phase precession of place cells in region CA3 of the hippocampus. The model describes the dynamics of two coupled point neurons--namely, a pyramidal cell and an interneuron, the latter of which is driven by a pacemaker input. Outside of the place field, the network displays a stable, background firing pattern that is locked to the theta rhythm. The pacemaker input drives the interneuron, which in turn activates the pyramidal cell. A single stimulus to the pyramidal cell from the dentate gyrus, simulating entrance into the place field, reorganizes the functional roles of the cells in the network for a number of cycles of the theta rhythm. In the reorganized network, the pyramidal cell drives the interneuron at a higher frequency than the theta frequency, thus causing a systematic precession relative to the theta input. The frequency of the pyramidal cell can vary to account for changes in the animal's running speed. The transient dynamics end after up to 360 degrees of phase precession when the pacemaker input to the interneuron occurs at a phase to return the network to the stable background firing pattern, thus signaling the end of the place field. Our model, in contrast to others, reports that phase precession is a temporally, and not spatially, controlled process. We also predict that like pyramidal cells, interneurons phase precess. Our model provides a mechanism for shutting off place cell firing after the animal has crossed the place field, and it explains the observed nearly 360 degrees of phase precession. We also describe how this model is consistent with a proposed autoassociative memory role of the CA3 region.

Encephalitogenic and immunogenic potential of the stress protein alphaB-crystallin in Biozzi ABH (H-2A(g7)) mice

The stress protein alphaB-crystallin is an immunodominant antigen in multiple sclerosis (MS)-affected myelin for human T cells and is expressed at elevated levels in MS lesions. Using bovine alphaB-crystallin and synthetic peptides based on mouse alphaB-crystallin the ability of this stress protein to induce experimental allergic encephalomyelitis (EAE) was screened in Biozzi ABH (H-2A(g7)) mice. While whole alphaB-crystallin and the immunodominant T cell epitopes (49-64, 73-88, 153-168) failed to induce disease the subdominant or cryptic epitope (1-16) was weakly encephalitogenic. The lack of encephalitogenicity of whole protein and dominant epitopes may be due to the low constitutive expression of alphaB-crystallin in the CNS combined with a state of peripheral tolerance suggested by the constitutive expression of alphaB-crystallin in secondary lymphoid tissues in ABH mice. Further evidence for a role of alphaB-crystallin in the progression of chronic relapsing neurological disease is suggested by the development of T cell responses to alphaB-crystallin during MOG-induced relapsing EAE as myelin damage accumulates. Together our data indicate that normal tolerising mechanisms in ABH mice prevent the induction of EAE by alphaB-crystallin while the subdominant or cryptic epitope is able to circumvent these mechanisms and contribute to pathogenic myelin-directed autoimmunity following T cell activation.

Familial arteriovenous malformations in siblings

BACKGROUND

Familial arteriovenous malformations (AVMs) of the brain are rare. We present two sisters with the same parents who harbored AVMs that were successfully treated.

METHODS

The elder sister presented with a unilateral migrainous type of headache overlying the right parietal area. The younger one suffered from exercise-induced headaches. Both were neurologically intact. Magnetic resonance imaging scans of the brain and cerebral angiography delineated the lesions. Both sisters underwent endovascular embolization followed by surgical resection.

RESULTS

Postoperatively, aside from a left inferior quadrantanopsia in the elder sister, both were neurologically intact.

CONCLUSIONS

We report the rare occurrence of familial AVMs in two siblings and review the literature of 14 reports. No genetic predisposition was found.

Neuroendovascular management of intracranial aneurysms

Intracranial aneurysms are a common disease constituting a significant health problem worldwide. Aneurysmal subarachnoid hemorrhage, cerebral aneurysms, classification of aneurysms, and management of aneurysms are discussed.

Nine cases of Merkel cell tumour

Merkel cell tumour is an aggressive neuroendocrine neoplasm arising in the dermis. Although only a few hundred cases have been reported worldwide, nine were seen in Nottingham between 1985 and early 1994. The patients were five women and four men age 63-88. One was the first Afro-Caribbean reported to have such a tumour. In no case was the diagnosis made clinically; histological and histochemical examination was necessary. Three of the patients died quickly with metastatic disease. The primary treatment is surgical excision. For advanced disease, radiotherapy is commonly beneficial.

Viral infection. II. Hemin induces overexpression of p67 as it partially prevents appearance of an active p67-deglycosylase in baculovirus-infected insect cells

The roles of p67-deglycosylase (p67-DG) in the regulation of protein synthesis in baculovirus-infected insect cells were studied. Like vaccinia viral infection, baculovirus infection of insect cells also induced the appearance of a p67-DG. However, p67-DG activity could not be detected because these cells do not contain a detectable level of p67. The baculovirus expression vector system (BEVS), however, promotes significant expression of cloned p67-cDNA. The expression of p67 was significantly enhanced by the addition of hemin to the growth medium. Maximum enhancement was observed at 5 microM hemin. Data suggest that hemin prevents the activation of latent p67-DG inside the cell and does not have any effect on p67 gene transcription. To gain a better understanding of the mechanism of p67-DG activation and hemin stimulation of p67 synthesis, we have now purified p67-DG from baculovirus-infected insect cells. We prepared antibodies against this protein. These antibodies reacted with a 105-kDa protein in cell extracts from the uninfected insect cells (Sf9), KRC-7, and L929 (animal cells). In addition, these antibodies reacted with an additional 60-kDa protein in the cell extracts of baculovirus-infected Sf9 cells and vaccinia virus-infected KRC-7 and L929 cells. Data are also presented to show that the antibodies against p67-DG reacted more efficiently (40%) with the 60-kDa protein in both hemin-deficient reticulocyte lysate and hemin-deficient baculovirus-infected cells. We suggest that hemin prevents the conversion of an inactive p67-DG into an active form possibly by covalent modification such as protein phosphorylation or protein glycosylation. The active form is more efficiently recognized by the p67-DG antibodies since these antibodies were prepared against the active form of p67-DG.

Viral infection. I. Regulation of protein synthesis during vaccinia viral infection of animal cells

Regulation of vaccinia viral infection was studied using three animal cell lines: KRC-7 (rat hepatoma), L929 (mouse fibroblast), and CV-1 (African green monkey kidney). KRC-7 is highly enriched in p67, a glycoprotein which protects eIF-2 alpha-subunit from phosphorylation by eIF-2 kinases. We report: (i) At 5 pfu per cell of the virus, KRC-7 is resistant to the virus. Other cells are sensitive. At 25 pfu per cell of the virus, KRC-7 is also sensitive to the virus. After productive viral infection, the cell extracts showed strong p67-DG activity and actively deglycosylated exogenous p67. After p67-deglycosylation, the cell extracts also phosphorylated eIF-2. (ii) The rate of synthesis of a major host protein (approximately 45 kDa) in infected L929 cells measured after 2 h of viral infection declined more than 50%. The rate declined thereafter. The rate of synthesis of host proteins in viral-resistant KRC-7 cells (infected with 5 pfu per cell of the virus) remained unchanged. The mechanism of resistance of KRC7 cells to vacinia virus at 5 pfu per cell of the virus was investigated. The p67 level in these cells was varied by growing the cells under different physiological conditions such as serum starvation and expression of p67-sense and p67-antisense DNA. At low p67 level in the cells, p67-DG is activated. This deglycosylates p67 and inactivates p67. This accompanies eIF-2 phosphorylation and shutoff of host protein synthesis. At high p67 level in the cells, activation of p67-DG is prevented. This prevents shut-off of host protein synthesis and viral growth.

p67 transcription regulates translation in serum-starved and mitogen-activated KRC-7 cells

The regulation of protein synthesis was studied in KRC-7 cells (rat hepatoma) grown in complete medium, during serum starvation, and mitogen activation. Upon serum starvation, the cells lost almost completely p67 mRNA, p67 protein, and protein synthesis activity. After phorbol 12-myristate 13-acetate addition, the same serum-starved cells regained p67 mRNA, p67 protein, and protein synthesis activity. Also, the extracts from the serum-starved cells phosphorylated the eukaryotic initiation factor-2 (eIF-2) alpha-subunit. This eIF-2 alpha-subunit phosphorylation was not observed when the extracts from either the cells grown in complete medium or mitogen-activated cells were used (Gupta, S., Wu, S., Chatterjee, N., Ilan, J., Ilan, J., Osterman, J. C., and Gupta, N. K. (1995) Gene Expr. 5, 113-122). We now report the following. 1) The eIF-2 kinase activity was the same in the cells grown in complete medium, after serum starvation, and subsequent mitogen stimulation. However, the eIF-2 kinase in the cells grown in complete medium and also after mitogen activation of the serum-starved cells cannot phosphorylate eIF-2 alpha-subunit as these cells contain p67. After removal of endogenous p67 by p67 antibodies, the extracts from all these cells similarly phosphorylated exogenously added eIF-2. 2) None of the cell extracts showed p67 deglycosylase activity. 3) The p67 mRNA was synthesized in serum-starved cells by expression of a p67 cDNA. The appearance of p67 mRNA in the serum-starved cells was accompanied by the appearance of p67 protein. Also, the rates of protein synthesis in the serum-starved cells were restored nearly to the level observed in the confluent cells. The expression of p67 cDNA also significantly increased protein synthesis rates in the cells grown in complete medium and in mitogen-activated cells. These results show that the loss of protein synthesis activity in serum-starved cells was due to loss of p67 mRNA. The expressed p67 mRNA was stable in serum-starved cells. These results, therefore, suggest that the loss of p67 mRNA in serum-starved cells is due to loss of p67 transcription. The p67 transcription regulates translation.

Functional reorganization in thalamocortical networks: transition between spindling and delta sleep rhythms

Thalamic reticularis, thalamocortical, and cortical cells participate in the 7-14-hz spindling rhythm of early sleep and the slower delta rhythms of deeper sleep, with different firing patterns. In this case study, showing the interactions of intrinsic and synaptic properties, a change in the conductance of one kind of cell effectively rewires the thalamocortical circuit, leading to the transition from the spindling to the delta rhythm. The two rhythms make different uses of the fast (GABAA) and slow (GABAB) inhibition generated by the thalamic reticularis cells.

Angiography of cerebral aneurysms

Magnetic resonance and computed tomographic angiography have been increasingly applied to the study of disease affecting the cerebral vasculature. Despite these advances, however, conventional cerebral angiography clearly remains the diagnostic gold standard and essential guide to any microneurosurgical or endovascular therapeutic decision concerning cerebral aneurysms. Detailed cerebral angiography is a dynamic study and is influenced by prior axial imaging. It should be tailored to the specific circumstance to obtain information required for selection of the most beneficial treatment.

Large scale isolation of expression vector cassette by magnetic triple helix affinity capture

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Mechanism of action of an eukaryotic initiation factor-2 (eIF-2) associated 67 kDa glycoprotein (p67) and an eIF-2 kinase (dsI)

Mechanism of regulation of eIF-2 alpha-subunit phosphorylation by dsI and p67 was studied. The results are as follows: (1) At low dsI concentration, p67 protected equimolar concentration of eIF-2. (2) At high dsI concentration, dsI efficiently phosphorylated eIF-2 alpha-subunit even when equimolar concentrations of both p67 and eIF-2 were present. Significantly increased p67 concentration was necessary to protect eIF-2 alpha-subunit at high dsI concentration. (3) dsI was also phosphorylated as it phosphorylated eIF-2 alpha-subunit. p67 inhibited both eIF-2 alpha-subunit and dsI phosphorylation similarly. (4) Although the [32P]-labelled dsI formed during the reaction could be effectively chased upon subsequent addition of excess unlabelled eIF-2 and ATP, the [32P] labelled eIF-2 formed under identical conditions, retained most of the radioactivity. (5) dsI coimmunoprecipitated with three subunit eIF-2 and p67 inhibited this coimmunoprecipitation reaction. It has been proposed: Three subunit eIF-2 and free p67 are in equilibrium with eIF-2 bound to p67 and, eIF-2.p67 complex is resistant to dsI phosphorylation. Activated dsI is already phosphorylated. At high concentration, dsI(P) can bind to free three subunit eIF-2 and form eIF-2.dsI(P) complex. dsI(P) in this complex then transfers its phosphoryl residue to eIF-2 and forms eIF-2 alpha(P) in an irreversible reaction. In a subsequent reaction, unphosphorylated dsI is autophosphorylated using [gamma 32P]-ATP and the cycle continues. Inhibition of eIF-2 alpha-subunit phosphorylation by p67 blocks this phosphorylation cycle and consequent dsI phosphorylation.

Regulation of eIF-2 alpha-subunit phosphorylation in reticulocyte lysate

An eIF-2 associated 67-kDa protein (p67) protects eIF-2 alpha-subunit from eIF-2 kinase(s) catalyzed phosphorylation and promotes protein synthesis in the presence of active eIF-2 kinase(s). p67 is a glycoprotein and contains multiple O-linked GlcNAc moieties. We have now studied the roles of hemin, p67, and the glycosyl residues on p67 in the regulation of eIF-2 alpha-subunit phosphorylation in reticulocyte lysates. The results are as follows: (i) Both hemin and p67 inhibited HRI (heme-regulated protein synthesis inhibitor) and dsI (double-stranded RNA activated protein synthesis inhibitor) catalyzed phosphorylation of eIF-2 alpha-subunit in vitro. However, only hemin, and not p67, inhibited casein kinase catalyzed phosphorylation of eIF-2 beta-subunit. (ii) Only p67, and not hemin, inhibited eIF-2 alpha-subunit phosphorylation by eIF-2 kinase(s) in reticulocyte lysate. Significant eIF-2 alpha-subunit phosphorylation was observed even in the presence of hemin when p67 in the reticulocyte lysate was removed by treatment with p67 antibodies. (iii) Reticulocyte lysate contains a p67-deglycosylase in latent form, and hemin prevents activation of this deglycosylase. In the absence of hemin, this p67-deglycosylase is activated. Once activated in the absence of hemin, the activated deglycosylase deglycosylates p67, even in the presence of hemin. This inactivates p67 and allows eIF-2 kinase to phosphorylate eIF-2 alpha-subunit and inhibit protein synthesis. Protein synthesis in reticulocyte lysate is thus regulated by two novel cascades of covalent modifications: protein deglycosylation leading to protein phosphorylation.

Characteristics of the eukaryotic initiation factor 2 associated 67-kDa polypeptide

A eukaryotic initiation factor 2 (eIF-2) associated 67-kDa polypeptide (p67) protects the eIF-2 alpha-subunit from eIF-2 kinase(s) catalyzed phosphorylation, and this promotes protein synthesis in the presence of active eIF-2 kinase(s), [Datta, B., et al. (1988) Proc. Natl. Acad. Sci. U.S.A. 85, 3324-3328]. This report presents the results of studies related to characteristics of p67 action and the mechanism of p67:eIF-2 interaction: (1) p67 antibodies inhibited protein synthesis in hemin-supplemented rabbit reticulocyte lysates, and such inhibition was reversed by preincubation of the antibodies, specifically with p67. (2) p67 inhibited HRI- and dsI-catalyzed phosphorylations of the eIF-2 alpha-subunit and histones, but it did not inhibit casein kinase catalyzed phosphorylation of the eIF-2 beta-subunit. (3) p67 bound specifically to the eIF-2 gamma-subunit. p67 co-immunoprecipitated with the eIF-2 subunits when a p67/eIF-2 mixture was treated with p67 or eIF-2 subunit antibodies and protein A agarose. However, when eIF-2 was preincubated specifically with the eIF-2 gamma-subunit antibodies, subsequent co-immunoprecipitation of p67 with the eIF-2 subunits was completely inhibited. Similarly, preincubation of p67 and p67 antibodies prevented subsequent p67 binding to eIF-2. Preincubation of eIF-2, with either eIF-2 alpha- or beta-subunit antibodies, had no effect on p67 co-immunoprecipitation with the eIF-2 subunits. (4) p67:eIF-2 interaction is necessary for p67 activity to protect the eIF-2 alpha-subunit from eIF-2 kinase(s) catalyzed phosphorylation.(ABSTRACT TRUNCATED AT 250 WORDS)

Syphilitic meningitis causing paraparesis in an HIV-negative woman

Syphilitic meningitis, which can occur near the time of secondary syphilis, is frequently asymptomatic. There has been one recent report of an HIV-positive patient who developed syphilitic polyradiculopathy following a recent history of secondary syphilis. We describe an HIV-negative woman in whom paraparesis occurred secondary to syphilitic meningitis. Complete recovery followed a course of high-dose intravenous penicillin therapy, emphasizing the treatable nature of this cause of paraparesis.

Computer simulations of chondrocytic clone behaviour in rabbit growth plates

The growth behaviour of chondrocytic clones in the cell columns of the proximal tibial growth plates of young rabbits was modelled in computer simulations. Simulations were performed, modelling either clones in large groups of columns or clones in one single column. The former were based on morphological data and measurements of cell columns from an earlier study while the latter utilised previous findings of cellular kinetics in rabbit growth plates. Simulation results that resembled most closely the actual observations on rabbit growth plates were those in which a distribution of values was assumed both for clone length (ranging from 1000 to 2000 microns) and for the lengths of the discontinuities between clones. When the assumption was made in the models that the disappearing (metaphyseal) end of an 'old' clone moved more rapidly than the developing (epiphyseal) end of a 'new' clone, replacing the former, the length of the discontinuity between these two clones increased with time. This assumption, which could be modelled in the simulations of clones in a single column based on cell growth behaviour, was found to provide an explanation for an earlier finding that there are more short columns at the epiphyseal side than at the metaphyseal side of a growth plate.