Tularaemia in Minnesota: case report and brief epidemiology

The 2008 case presented here of tularaemia in a cat and its owner occurred in an urban setting and was associated with animal contact, a relatively rare mode of transmission in Minnesota in recent years. Response to this case exemplified a 'One Health' approach involving pre-existing relationships, cooperation between multiple disciplines and laboratory infrastructure that facilitated information sharing.

Endosomal compartmentalization in three dimensions: implications for membrane fusion

Endosomes are major sorting stations in the endocytic route that send proteins and lipids to multiple destinations in the cell, including the cell surface, Golgi complex, and lysosomes. They have an intricate architecture of internal membrane structures enclosed by an outer membrane. Recycling proteins remain on the outer membrane, whereas proteins that are destined for degradation in the lysosome are sorted to the interior. Recently, a retrograde pathway was discovered whereby molecules, like MHC class II of the immune system, return from the internal structures to the outer membrane, allowing their further transport to the cell surface for T cell activation. Whether this return involves back fusion of free vesicles with the outer membrane, or occurs via the continuity of the two membrane domains, is an unanswered question. By electron tomography of cryo-immobilized cells we now demonstrate that, in multivesicular endosomes of B-lymphocytes and dendritic cells, the inner membranes are free vesicles. Hence, protein transport from inner to outer membranes cannot occur laterally in the plane of the membrane, but requires fusion between the two membrane domains. This implies the existence of an intracellular machinery that mediates fusion between the exoplasmic leaflets of the membranes involved, which is opposite to regular intracellular fusion between cytoplasmic leaflets. In addition, our 3D reconstructions reveal the presence of clathrin-coated areas at the cytoplasmic face of the outer membrane, known to participate in protein sorting to the endosomal interior. Interestingly, profiles reminiscent of inward budding vesicles were often in close proximity to the coats.

Increase in meningococcal disease associated with the emergence of a novel ST-11 variant of serogroup C Neisseria meningitidis in Victoria, Australia, 1999-2000

In the years 1999-2000, there was an increase in the incidence of meningococcal disease in Victoria, largely caused by Neisseria meningitidis serogroup C. This change was associated with a shift in age distribution of cases, with relatively more disease appearing in the 15-29 year age group, and with 40/58 serogroup C isolates in 2000 exhibiting a new macrorestriction pattern (pattern A). Thirty-four of 52 pattern A isolates tested displayed the novel phenotype C:2a:P1.4, and were consistently porA VR type P1.7-2,4 by DNA sequencing. Nine of 10 representative pattern A isolates analysed displayed a housekeeping gene allele profile (ST-11) that is characteristic of the electrophoretic type (ET)-15 variant that has caused outbreaks in Canada, the Czech Republic and Greece. Meningococci belonging to the ST-11 complex that were isolated in Victoria prior to 1999 did not display either restriction pattern A or PorA VR type P1.7-2,4.

Antigen loading of MHC class I molecules in the endocytic tract

Major histocompatibility complex (MHC) class I molecules bind antigenic peptides that are translocated from the cytosol into the endoplasmic reticulum by the transporter associated with antigen processing. MHC class I loading independent of this transporter also exists and involves peptides derived from exogenously acquired antigens. Thus far, a detailed characterization of the intracellular compartments involved in this pathway is lacking. In the present study, we have used the model system in which peptides derived from measles virus protein F are presented to cytotoxic T cells by B-lymphoblastoid cells that lack the peptide transporter. Inhibition of T cell activation by the lysosomotropic drug ammoniumchloride indicated that endocytic compartments were involved in the class I presentation of this antigen. Using immunoelectron microscopy, we demonstrate that class I molecules and virus protein F co-localized in multivesicular endosomes and lysosomes. Surprisingly, these compartments expressed high levels of class II molecules, and further characterization identified them as MHC class II compartments. In addition, we show that class I molecules co-localized with class II molecules on purified exosomes, the internal vesicles of multivesicular endosomes that are secreted upon fusion of these endosomes with the plasma membrane. Finally, dendritic cells, crucial for the induction of primary immune responses, also displayed class I in endosomes and on exosomes.

Multiple outbreaks of Norwalk-like virus gastro-enteritis associated with a Mediterranean-style restaurant

The role of diverse infectious agents, particularly Norwalk-like viruses (NLV), in three successive gastro-enteritis outbreaks in one setting (a restaurant) was evaluated. Methods included standard bacteriological tests, specific tests for Escherichia coli, tests for verocytotoxins, electron microscopy (EM) for viruses and reverse transcription-PCR (RT-PCR) methodology for NLV. No pathogenic bacteria were detected. Verocytotoxin genes, although detected by PCR in the first outbreak, could not be confirmed in the E. coli isolated, so they did not appear to be of significance. NLV was the main agent detected in each of the three outbreaks. DNA sequencing and phylogenetic analysis of the amplified products obtained from the RT-PCR positive specimens indicated that only one NLV strain was involved in each outbreak, but the NLV strains responsible for the three outbreaks were different from each other. PCR technology for detection of NLV proved highly sensitive, but failed to detect one specimen which was positive by EM. The restaurant associated with the outbreaks is a Mediterranean-style restaurant where food from a common platter is typically eaten with fingers. The findings indicate that NLV was introduced by guests or staff and was not due to a long-term reservoir within the setting.

Platelet alpha2A-adrenoceptor function in major depression: Gi coupling, effects of imipramine and relationship to treatment outcome

Studies suggest alpha2A-adrenoceptors (alpha(2A)AR) dysregulation in major depressive disorder (MDD). Platelet alpha(2A)ARs exist in high- and low-conformational states that are regulated by Gi protein. Although alpha(2A)AR coupling to Gi protein plays an important role in signal transduction and is modulated by antidepressants, it has not been previously investigated. Alpha2AR density in the high- and low-conformational states, agonist affinity and coupling efficiency were investigated in 27 healthy control subjects, 23 drug-free MDD patients and 16 patients after imipramine treatment using [3H]yohimbine saturation and norepinephrine displacement of [3H]yohimbine binding experiments. Coupling measures were derived from NE-displacement experiments. Patients had significantly higher alpha(2A)AR density, particularly in the high-conformational state, than control subjects. Coupling indices were normal in patients. High pre-treatment agonist affinity to the receptor in the high-conformational state and normal coupling predicted positive treatment outcome. Decreased coupling to Gi predicted a negative treatment outcome. Imipramine induced uncoupling (-11%) and redistribution of receptor density in treatment responders only, but had no effect on alpha(2A)AR coupling or density in treatment non-responders. Increased alpha(2A)AR density may represent a trait marker in MDD. The results provide indirect evidence for abnormal protein kinase A (PKA) and protein kinase C (PKC) in MDD which may be pursued in future investigations.

Neutrophil beta(2)-adrenoceptor function in major depression: G(s) coupling, effects of imipramine and relationship to treatment outcome

Abnormal beta(2)-adrenoceptor density and beta(2)-adrenoceptor-mediated cyclic adenosine monophosphate (cAMP) responses were inconsistently reported in major depressive disorder. Tricyclic antidepressants downregulate beta-adrenoceptor density and decrease coupling to G(s) protein. Abnormal beta-adrenoceptor coupling may exist in major depressive disorder and may relate to treatment response. We investigated beta(2)-adrenoceptor coupling to G(s) protein in 25 controls, 23 major depressive disorder drug-free patients and 16 major depressive disorder patients after chronic imipramine treatment using agonist displacement experiments. Pretreatment beta(2)-adrenoceptor coupling and density were normal in patients as a whole. Chronic imipramine induced beta(2)-adrenoceptor uncoupling. This effect was observed in treatment responders who had increased beta(2)-adrenoceptor density in the high-conformational state and supercoupling prior to treatment. Beta(2)-adrenoceptor density decreased after imipramine treatment. Treatment non-responders had seemingly normal pretreatment beta(2)-adrenoceptor function, which was not changed by imipramine. Differences in beta(2)-adrenoceptor regulation in major depressive disorder may underlie treatment response. The results indirectly implicate abnormal agonist-mediated beta(2)-adrenoceptor gene expression, protein kinase A, and protein kinase C in major depressive disorder.

Combined infection of Norwalk-like virus and verotoxin-producing bacteria associated with a gastroenteritis outbreak

Detection of multiple pathogens, particularly a combination of viruses and bacteria, is infrequently documented in outbreaks of gastroenteritis. This paper reports the presence of Norwalk-like virus (NLV) and enterohaemorrhagic verotoxin-producing Escherichia coli in one individual, and NLV and verotoxin-producing Aeromonas sobria in another individual, both part of a large gastroenteritis outbreak. The causes of gastroenteritis in such outbreaks may be more complex than previously thought.

The tetraspan protein CD82 is a resident of MHC class II compartments where it associates with HLA-DR, -DM, and -DO molecules

In specialized APCs, MHC class II molecules are synthesized in the endoplasmic reticulum and transported through the Golgi apparatus to organelles of the endocytic pathway collectively called MHC class II compartments (MIICs). There, the class II-associated invariant chain is degraded, and peptides derived from internalized Ag bind to empty class II in a reaction that is facilitated by the class II-like molecule HLA-DM. An mAb raised to highly purified, immunoisolated MIICs from human B lymphoblastoid cells recognized CD82, a member of the tetraspan family of integral membrane proteins. Subcellular fractionation, immunofluorescence microscopy, and immunoelectron microscopy showed that CD82 is highly enriched in MIICs, particularly in their internal membranes. Coprecipitation analysis showed that CD82 associates in MIICs with class II, DM, and HLA-DO (an inhibitor of peptide loading that binds DM). Similar experiments showed CD63, another tetraspan protein found in MIICs, also associates with these molecules in the compartment and that CD82 and CD63 associate with each other. Preclearing experiments demonstrated that both CD82 and CD63 form complexes with DM-associated class II and DM-associated DO. The ability of CD82 and CD63 to form complexes with class II, DM, and DO in MIICs suggests that the tetraspan proteins may play an important role in the late stages of MHC class II maturation.

Selective enrichment of tetraspan proteins on the internal vesicles of multivesicular endosomes and on exosomes secreted by human B-lymphocytes

Association of major histocompatibility complex (MHC) class II molecules with peptides occurs in a series of endocytic vacuoles, termed MHC class II-enriched compartments (MIICs). Morphological criteria have defined several types of MIICs, including multivesicular MIICs, which are composed of 50-60-nm vesicles surrounded by a limiting membrane. Multivesicular MIICs can fuse with the plasma membrane, thereby releasing their internal vesicles into the extracellular space. The externalized vesicles, termed exosomes, carry MHC class II and can stimulate T-cells in vitro. In this study, we show that exosomes are enriched in the co-stimulatory molecule CD86 and in several tetraspan proteins, including CD37, CD53, CD63, CD81, and CD82. Interestingly, subcellular localization of these molecules revealed that they were concentrated on the internal membranes of multivesicular MIICs. In contrast to the tetraspans, other membrane proteins of MIICs, such as HLA-DM, Lamp-1, and Lamp-2, were mainly localized to the limiting membrane and were hardly detectable on the internal membranes of MIICs nor on exosomes. Because internal vesicles of multivesicular MIICs are thought to originate from inward budding of the limiting membrane, the differential distribution of membrane proteins on the internal and limiting membranes of MIICs has to be driven by active protein sorting.

Nicotinic receptor desensitization and sensory gating deficits in schizophrenia

BACKGROUND

Nicotinic receptor dysfunction is a possible mechanism of the abnormal sensory gating observed in schizophrenia with the P50 auditory event-related potential. Although nicotinic receptors normally desensitize after activation by acetylcholine or nicotine, pathologically increased desensitization might cause receptor dysfunction in schizophrenia. To examine this possibility, central cholinergic neuronal activity was diminished by allowing schizophrenic patients to sleep briefly, after which they experienced a transient period of normal P50 gating, consistent with receptor resensitization during the absence of cholinergic stimulation. A critical test of the mechanism is whether this resensitization is blocked by concurrent administration of nicotine, which would provide continuous receptor stimulation.

METHODS

Six schizophrenic patients repeated the sleep experiment during nicotine exposure from a dermal patch, in a double-blind, placebo-controlled design.

RESULTS

The normalization of P50 gating immediately postsleep was replicated in the placebo arm, but this effect was decreased in all six patients during exposure to nicotine.

CONCLUSIONS

The results suggest that nicotinic receptor desensitization is responsible for the loss of P50 gating in schizophrenia.

Mannose 6-phosphate receptors are sorted from immature secretory granules via adaptor protein AP-1, clathrin, and syntaxin 6-positive vesicles

The occurrence of clathrin-coated buds on immature granules (IGs) of the regulated secretory pathway suggests that specific transmembrane proteins are sorted into these buds through interaction with cytosolic adaptor proteins. By quantitative immunoelectron microscopy of rat endocrine pancreatic beta cells and exocrine parotid and pancreatic cells, we show for the first time that the mannose 6-phosphate receptors (MPRs) for lysosomal enzyme sorting colocalize with the AP-1 adaptor in clathrin-coated buds on IGs. Furthermore, the concentrations of both MPR and AP-1 decline by approximately 90% as the granules mature. Concomitantly, in exocrine secretory cells lysosomal proenzymes enter and then are sorted out of IGs, just as was previously observed in beta cells (Kuliawat, R., J. Klumperman, T. Ludwig, and P. Arvan. 1997. J. Cell Biol. 137:595-608). The exit of MPRs in AP-1/clathrin-coated buds is selective, indicated by the fact that the membrane protein phogrin is not removed from maturing granules. We have also made the first observation of a soluble N-ethylmaleimide-sensitive factor attachment protein receptor, syntaxin 6, which has been implicated in clathrin-coated vesicle trafficking from the TGN to endosomes (Bock, J.B., J. Klumperman, S. Davanger, and R.H. Scheller. 1997. Mol. Biol. Cell. 8:1261-1271) that enters and then exits the regulated secretory pathway during granule maturation. Thus, we hypothesize that during secretory granule maturation, MPR-ligand complexes and syntaxin 6 are removed from IGs by AP-1/clathrin-coated vesicles, and then delivered to endosomes.

Association between corticosteroid use and vertebral fractures in older men with chronic obstructive pulmonary disease

Osteoporosis is a major complication of long-term corticosteroid administration, but the magnitude of the effect in patients with chronic obstructive pulmonary disease (COPD) is not well defined. In a cross-sectional study, we evaluated the association between steroid use and vertebral fractures in 312 men, 50 yr of age or older, with COPD. Subjects were evaluated according to their corticosteroid use: Never Steroid Users (NSU) (n = 117), Inhaled Steroid Users (ISU) (n = 70), and Systemic Steroid Users (SSU) (n = 125). The prevalence of one or more vertebral fractures was 48.7% in the NSU group, 57.1% in the ISU group, and 63.3% in the SSU group. Compared with NSU, SSU were two times as likely to have one or more vertebral fractures: age-adjusted odds ratio (OR) = 1.80; 95% CI, 1.08 to 3.07. This relationship was primarily due to a strong association between continuous systemic steroid use and vertebral fractures: age-adjusted OR = 2.36; 95% CI, 1.26 to 4.38. In addition, fractures in SSU were more likely to be multiple and more severe. A weaker relationship existed between inhaled steroid use and vertebral fractures: age-adjusted OR = 1.35; 95% CI, 0.77 to 2.56 compared with NSU. These data indicate that vertebral fractures are common in older men with COPD; the likelihood of these fractures is greatest in those men using continuous systemic steroids.

Major histocompatibility complex class II compartments in human and mouse B lymphoblasts represent conventional endocytic compartments

In most human and mouse antigen-presenting cells, the majority of intracellular major histocompatibility complex (MHC) class II molecules resides in late endocytic MHC class II compartments (MIICs), thought to function in antigen processing and peptide loading. However, in mouse A20 B cells, early endocytic class II-containing vesicles (CIIVs) have been reported to contain most of the intracellular MHC class II molecules and have also been implicated in formation of MHC class II-peptide complexes. To address this discrepancy, we have studied in great detail the endocytic pathways of both a human (6H5.DM) and a mouse (A20.Ab) B cell line. Using quantitative immunoelectron microscopy on cryosections of cells that had been pulse-chased with transferrin-HRP or BSA-gold as endocytic tracers, we have identified up to six endocytic subcompartments including an early MIIC type enriched in invariant chain, suggesting that it serves as an important entrance to the endocytic pathway for newly synthesized MHC class II/invariant chain complexes. In addition, early MIICs represented the earliest endocytic compartment containing MHC class II- peptide complexes, as shown by using an antibody against an abundant endogenous class II-peptide complex. The early MIIC exhibited several though not all of the characteristics reported for the CIIV and was situated just downstream of early endosomes. We have not encountered any special class II-containing endocytic structures besides those normally present in nonantigen-presenting cells. Our results therefore suggest that B cells use conventional endocytic compartments rather than having developed a unique compartment to accomplish MHC class II presentation.

Characteristics of patients with substance abuse diagnoses on a general psychiatry unit in a VA Medical Center

OBJECTIVE

The study examined characteristics associated with substance abuse among patients on a VA general inpatient psychiatry unit.

METHODS

A total of 452 consecutive discharge summaries from a six-month period were examined for a recorded diagnosis of psychoactive substance abuse or dependence and evidence of negative social or health effects from the use of drugs or alcohol within one month of admission. The summaries were divided into three groups-no active substance abuse, active alcohol dependence, and two or more active substance dependencies. The demographic, diagnostic, and treatment outcome characteristics of the three groups were compared.

RESULTS

Fifty-eight percent of the summaries included evidence of dependence on at least one substance. The three study groups differed in age, gender, racial mix, and psychiatric comorbidity. The group with no active substance abuse had an older mean age, included a higher proportion of women, and had a higher proportion of patients with bipolar disorder (manic), unipolar depression, and dementia. The group with two or more substance dependencies had a younger mean age, a higher proportion of African Americans, and a higher proportion of patients with cluster B personality disorders and schizophrenia. The group with alcohol dependence only was intermediate in age between the other two groups and had a racial mix similar to that of the group with no substance abuse.

CONCLUSIONS

A high proportion of veterans seeking mental health care have substance dependencies. The relatively distinct profiles of the patients who abuse alcohol only and those who abuse more than one substance suggest the need for programs specifically tailored to each of these two groups.

Gating of auditory P50 in schizophrenics: unique effects of clozapine

Schizophrenic patients have a deficit in the ability to filter sensory stimuli, which can be demonstrated in several psychophysiological paradigms. For example, most unmedicated schizophrenic subjects fail to decrement the P50 auditory evoked response to the second of paired stimuli, when the interstimulus interval is 500 msec. This sensory gating deficit persists in schizophrenics treated with typical antipsychotics, even if they show significant clinical improvement. When the interstimulus interval is 100 msec, most schizophrenics exhibit impaired gating while acutely ill, but normalize with treatment. Clozapine, the prototypic atypical antipsychotic medication, is clinically more effective than conventional neuroleptics in a significant proportion of schizophrenics refractory to other drug treatment. Nine schizophrenic subjects who were refractory to conventional neuroleptic treatment were studied while being treated with typical neuroleptics and then restudied after 1 month's treatment with clozapine. In the six clozapine responders, there was significant improvement of P50 gating at the 500 msec interval. At the 100 msec interval there was an inverse relationship between sensory gating of P50 and clozapine dose, independent of clinical response. Thus, although this can only be considered preliminary data because of the small number of subjects, it appears that clozapine, compared to typical neuroleptics, has distinct effects on P50 gating.

Nicotinic receptor function in schizophrenia

Schizophrenia can be partially characterized by deficits in sensory processing. Biochemical, molecular, and genetic studies of one such endophenotype, the P50 auditory-evoked potential gating deficit, suggest that one of the neuronal nicotinic receptors, the alpha 7 nicotinic receptor, may function in an inhibitory neuronal pathway involved in this phenotype. The P50 deficit is normalized in nongating subjects by nicotine. Although most schizophrenia patients are heavy smokers, the effects of nicotine may be transient, as alpha 7 receptors are known to desensitize rapidly. In an animal model of the P50 gating deficit, antagonists of the alpha 7 nicotinic receptor block normal gating of the second of paired auditory stimuli. Regional localization of receptor expression includes areas known to function in sensory filtering. An inhibitory mechanism, in the hippocampus, may involve nicotinic stimulation of gamma-aminobutyric acid (GABA)ergic interneurons, resulting in decreased response to repetitive stimuli. Expression of the alpha 7 receptor is decreased in hippocampal brain tissue, dissected postmortem, from schizophrenia subjects. The P50 deficit is inherited in schizophrenia pedigrees, but it is not sufficient for disease development and thus represents a predisposition factor. Linkage analysis between the P50 deficit in multiplex schizophrenia pedigrees and deoxyribonucleic acid (DNA) markers throughout the genome yielded positive lod scores to DNA markers mapping to a region of chromosome 15 containing the alpha 7 nicotinic receptor gene. Elucidation of possible interactions of the P50 with other factors, known to be important in the etiology of the disease, is important in determining an overall pathobiology of schizophrenia.

Normalization of the auditory P50 gating deficit of schizophrenic patients after non-REM but not REM sleep

Diminished suppression of the P50 response to repeated auditory stimuli is one example of a deficit in elementary sensory processing in schizophrenia. Normal subjects suppress the response to the second of two paired auditory stimuli. Although normal suppression is occasionally observed in schizophrenic patients, it generally disappears with subsequent testing. We have previously reported that slow wave sleep (SWS) transiently normalized suppression in schizophrenic patients and that the degree of suppression was positively correlated with the depth of SWS attained. We hypothesized that schizophrenic patients may have a defect that causes a neuronal mechanism to fail after brief use and that its activity can be restored by a transient period of inactivity. The present study examined whether this effect of sleep in schizophrenic patients is specific to SWS or is due to nonspecific factors involved in any period of unconsciousness. After baseline recordings, 10 schizophrenic subjects were allowed a period of sleep until they attained rapid-eye-movement (REM) sleep. They were awakened at the end of the REM period, and postsleep recordings were obtained. REM-stage sleep failed to normalize suppression in any of the schizophrenic subjects. P50 suppression was subsequently assessed after a period of non-REM (NREM) sleep. Subjects who reached stage-2 sleep did demonstrate a transient correction in auditory gating. These results replicate our previous findings and suggest that the sleep effect is specific to NREM sleep. A desensitized nicotinic receptor that is resensitized during cholinergic inactivity in NREM sleep is one possible mechanism for this effect.

Schizophrenia and nicotinic receptors

Patients with schizophrenia often cannot respond to important features of their environment and filter out irrelevant stimuli. This dysfunction could be related to an underlying defect in inhibition--i.e., the brain's ability to alter its sensitivity to repeated stimuli. One of the neuronal mechanisms responsible for such inhibitory gating involves the activation of cholinergic nicotinic receptors in the hippocampus. These receptors are diminished in many specimens of hippocampal brain tissue obtained postmortem from schizophrenic patients. In living schizophrenic patients, stimulation of cholinergic receptors by nicotine transiently restores inhibitory gating of evoked responses to sensory stimuli. Many people with schizophrenia are heavy smokers, but the properties of the nicotinic receptor favor only short-term activation, which may explain why cigarette smoking is only a transient symptomatic remedy. This paper reviews the clinical phenomenology of inhibitory gating deficits in people with schizophrenia, the neurobiology of such gating mechanisms, and the evidence that some individuals with the disorder may have a heritable deficit in the nicotinic cholinergic receptors involved in this neurobiological function. Inhibitory gating deficits are only partly normalized by neuroleptic drugs and are thus a target for new therapeutic strategies for schizophrenia.

Fine motor performance in schizophrenia

Peripheral and central aspects of motor dysfunction were assessed in 12 schizophrenic and 12 normal subjects, using a test of control of finger movement based on the widely used smooth pursuit eye movement task. This was performed in order to investigate the basis of neuromotor dysfunction in schizophrenia. In this task, subjects used finger movement to track a visual target. Simultaneously, an electromyogram of the extensor digitorum communis, the primary muscle utilized in the task, was recorded. Smooth pursuit eye movements were also assessed. Accuracy of finger-based and smooth-pursuit eye movement tracking was analyzed by fast Fourier transform and expressed as a log signal-to-noise ratio. The electromyograms were analyzed by motor unit potential discrimination and by interspike interval histography. Schizophrenics demonstrated significantly poorer finger tracking than did controls, with a mean score of 2.01 +/- 0.63 (SD) versus 2.81 +/- 0.42 (t = 3.52, d.f. = 21, p < 0.005). However, there was no evidence for motor-unit dysfunction. Schizophrenics also performed more poorly on smooth-pursuit eye movement, with a mean score of 2.06 +/- 0.62 versus 3.33 +/- 1.21 (t = 3.21, d.f. = 22, p < 0.005). Severity of extrapyramidal symptoms was correlated with poorer performance on the finger tracking task, but not smooth-pursuit eye movement. These findings support the hypothesis that schizophrenics' tracking abnormalities are due to central nervous system deficits rather than peripheral pathology.

Normalization of auditory sensory gating in schizophrenic patients after a brief period for sleep

Diminished suppression of the P50 component of the evoked potential following repeated auditory stimuli is one example of a deficit in elementary sensory processing in schizophrenia. Normal subjects suppress the P50 evoked potential to the second of two paired auditory stimuli. Although normal P50 suppression is occasionally observed in schizophrenic patients, it generally disappears with subsequent testing. The object of this experiment was to determine conditions for the reproducible normalization of P50 suppression in schizophrenic patients. After baseline recordings, 12 schizophrenic subjects were allowed to sleep for 10 minutes. The depth of sleep obtained was assessed by electroencephalography (EEG). Normalization of P50 suppression was observed for approximately 3 minutes in all subjects who entered slow wave sleep, but not in those whose EEG records remained desynchronized. Some change was even observed in subjects who had only persistent alpha waves. The amount of normalization was correlated with the deepest stage of sleep reached. Normal control subjects did not show this phenomenon but instead had a transient decrease in sensory gating after waking from sleep. The results suggest that schizophrenic patients may have a defect that causes a neuronal mechanism critical to sensory gating to fail after brief use, although its activity can be transiently restored by a short period of inactivity. A rapidly desensitized neurotransmitter receptor is one possible mechanism of such an effect.

Concurrent medical illness in the schizophrenic patient. Epidemiology, diagnosis, and management

The management of the medically ill schizophrenic patient presents a dual dilemma for the physician. The patient may have a serious medical illness that must be diagnosed and effectively treated, yet the patient's psychiatric disorder may interfere with effective management. Thus, undiagnosed and untreated medical illness can result in significant morbidity for schizophrenic patients. Because schizophrenic patients may appear to be less cooperative than medical patients without concurrent psychiatric illness, they can cause countertransference reactions on the part of physicians and nursing staff that can interfere with treatment. Schizophrenic patients also have deficits in the processing of sensory information. These deficits require the staff to make changes in management in order to facilitate the patient's ability to cooperate with treatment and to give reliable informed consent. A host of other factors complicate the medical management and treatment of schizophrenic patients. Such factors include medication side effects of psychotropic medication, the potential interactions between medications used to treat the patient's physical illness with psychotropics, pregnancy in the female patient, and the strength of the patient's support system. The ability to successfully diagnose and treat concurrent medical illness in the schizophrenic patient will depend on the physician's ability to be flexible and to understand the implications of the patient's underlying disorder for his relationship to hospital staff. This paper reviews some of the relevant literature and describes possible treatment strategies integrating what we know about schizophrenia with medical management.

31P NMR studies on the effect of phosphite on Phytophthora palmivora

31P NMR spectra were obtained from perchloric acid (PCA) and KOH extracts of Phytophthora palmivora mycelium. Signals indicating the presence of large amounts of short-chain polyphosphate were observed in the spectra of PCA extracts of mycelia grown under both low (0.1 mM) and high (10 mM) phosphate conditions. The mean chain length of polyphosphate was calculated from the relative areas of signals arising from terminal and internal P nuclei in the polyphosphate chain. The small amount of polyphosphate evident in the KOH extract had an average chain length similar to PCA-soluble polyphosphate. 32P tracer studies indicated that phosphorus in the PCA fraction accounted for between 50 and 60% of total phosphorus, the bulk of the remainder being divided between the lipid and KOH extracts. The presence of the fungicide phosphorous acid markedly reduced the average chain length of acid-soluble polyphosphate. This reduction occurred both under low-phosphate conditions, in which treatment with phosphorous acid retards growth, and under high-phosphate conditions, in which no significant growth retardation is observed. Treatment with phosphorous acid perturbed phosphorus distribution and lipid composition under low-phosphate conditions.

Molecules relevant for T cell-target cell interaction are present in cytolytic granules of human T lymphocytes

An ultrastructural analysis of human cytotoxic T lymphocyte-target cell (CTL-TC) interaction has been undertaken to enable a better understanding of the killing mechanism. Attention was focused on granules in the CTL, which are known to contain lethal compounds. Within the membrane-delimited cytotoxic granule an electron-dense core as well as numerous membrane vesicles were identified. In CTL-TC conjugates, specific membrane interactions take place, allowing the formation of intercellular clefts into which the granule cores and internal vesicles are released. T cell surface membrane molecules known to be involved in CTL-TC interaction (T cell receptor, CD3 and CD8) are present on the membranes of the granule cores and internal vesicles, facing outward. An explanation for this localization of the membrane may be found in the fact that the granule is connected with an endocytotic pathway. Moreover, the lumen of the granule is rich in the enzyme cathepsin D, which indicates an association with a lysosomal compartment. Exocytosed vesicles and cores are seen to adhere to the plasma membrane of the TC. Although the exact contents of the granule vesicles and core remain to be identified, we suggest that specific interaction of CTL membrane molecules on the cytolytic granule components with molecules on the plasma membrane of the TC may ensure the unidirectional delivery of the lethal hit.

Relations between the intracellular pathways of the receptors for transferrin, asialoglycoprotein, and mannose 6-phosphate in human hepatoma cells

We compared the intracellular pathways of the transferrin receptor (TfR) with those of the asialoglycoprotein receptor (ASGPR) and the cation-independent mannose 6-phosphate receptor (MPR)/insulin-like growth factor II receptor during endocytosis in Hep G2 cells. Cells were allowed to endocytose a conjugate of horseradish peroxidase and transferrin (Tf/HRP) via the TfR system. Postnuclear supernatants of homogenized cells were incubated with 3,3'-diaminobenzidine (DAB) and H2O2. Peroxidase-catalyzed oxidation of DAB within Tf/HRP-containing endosomes cross-linked their contents to DAB polymer. The cross-linking efficiency was dependent on the intravesicular Tf/HRP concentration. The loss of detectable receptors from samples of cell homogenates treated with DAB/H2O2 was used as a measure of colocalization with Tf/HRP. To compare the distribution of internalized plasma membrane receptors with Tf/HRP, cells were first surface-labeled with 125I at 0 degrees C. After uptake of surface 125I-labeled receptors at 37 degrees C in the presence of Tf/HRP, proteinase K was used at 0 degrees C to remove receptors remaining at the plasma membrane. Endocytosed receptors were isolated by means of immunoprecipitation. 125I-TfR and 125I-ASGPR were not sorted from endocytosed Tf/HRP. 125I-MPR initially also resided in Tf/HRP-containing compartments, however 70% was sorted from the Tf/HRP pathway between 20 and 45 min after uptake. To study the accessibility of total intracellular receptor pools to endocytosed Tf/HRP, nonlabeled cells were used, and the receptors were detected by means of Western blotting. The entire intracellular TfR population, but only 70 and 50% of ASGPR and MPR, respectively, were accessible to endocytosed Tf/HRP. These steady-state levels were reached by 10 min of continuous Tf/HRP uptake at 37 degrees C. We conclude that 30% of the intracellular ASGPR pool is not involved in endocytosis (i.e., is silent). Double-labeling immunoelectron microscopy on DAB-labeled cells showed a considerable pool of ASGPR in secretory albumin-positive, Tf/HRP-negative, trans-Golgi reticulum. We suggest that this pool represents the silent ASGPR that has been biochemically determined. A model of receptor transport routes is presented and discussed.

Accelerated ion fluxes during differentiation in zoospores of Phytophthora palmivora

Zoospores of Phytophthora palmivora show increased fluxes of Na+ and Ca2+ 3-5 min after they have been stimulated to differentiate with pectin. Both spontaneous and pectin-induced encystment are reduced below pH 6 and accelerated above pH 7. The ionophores monensin and A23187 induce slow differentiation when added together, but not when added separately. Ethanol (0.5%) also induces slow differentiation. Amiloride and verapamil inhibit pectin-induced differentiation and also reduce the onset of the Na+ and Ca2+ flux. A requirement for Ca2+ for differentiation is confirmed, but a requirement for Na+ could not be demonstrated.

The pathways of endocytosed transferrin and secretory protein are connected in the trans-Golgi reticulum

We used a conjugate of transferrin and horseradish peroxidase (Tf/HRP) to label the intracellular transferrin receptor route in the human hepatoma cell line HepG2. The recycling kinetics of [125I]Tf/HRP were similar to those of unmodified [125I]Tf, implying identical routes for both ligands. 3,3'Diaminobenzidine (DAB)-cytochemistry was performed on post-nuclear supernatants of homogenates of cells which were incubated with both Tf/HRP and [125I]Tf, and caused two different effects: (a) the equilibrium density of [125I]Tf containing microsomes in a Percoll density gradient was increased, and (b) the amount of immunoprecipitable [125I]Tf from density-shifted lysed microsomes was only 20% of that of nonDAB treated microsomes. The whole biosynthetic route of alpha 1-antitrypsin (AT), a typical secretory glycoprotein in HepG2 cells, was labeled during a 60-min incubation with [35S]methionine. DAB cytochemistry was performed on post-nuclear supernatants of homogenates of cells which were also incubated with Tf/HRP. DAB cytochemistry caused approximately 40% of microsome-associated "complex" glycosylated [35S]alpha 1-antitrypsin ([35S]c-AT) to shift in a Percoll density gradient. Only part of the density shifted [35S]c-AT could be recovered by immunoprecipitation. A maximum effect was measured already after 10 min of Tf/HRP uptake. The density distribution of the "high mannose" glycosylated form of 35S-alpha 1-anti-trypsin [( 35S]hm-AT) was not affected by Tf/HRP. If in addition to Tf/HRP also an excess of non-conjugated transferrin was present in the medium, [35S]c-AT was not accessible for Tf/HRP, showing the involvement of the transferrin receptor (TfR) in the process. Furthermore, we show that if Tf/HRP and [35S]c-AT were located in different vesicles, the density distribution of [35S]c-AT was not affected by DAB-cytochemistry. Pulse-labeling with [35S]methionine was used to show that [35S]c-AT became accessible to endocytosed Tf/HRP minutes after acquirement of the complex configuration. A common intracellular localization of endocytosed Tf/HRP and secretory protein could be confirmed by immuno-electron microscopy: cryosections labeled with anti-albumin (protein A-colloidal gold) as well as DAB reaction product showed double-labeling in the trans-Golgi reticulum.

Calcium efflux associated with encystment of Phytophthora palmivora zoospores

Zoospores of the fungus Phytophthora palmivora, pre-labeled with 45Ca, excreted up to 30% of their total 45Ca when stimulated to encyst. Excretion was essentially completed within 90 sec of the application of the stimulus. Encystment of the population was completed within 5 min. Four different stimuli were used: pectin addition (420 micrograms ml-1), Sr2+ addition (5 mM), cyclic AMP addition (6.7 mM) and mechanical agitation. The kinetics and amount of Ca excretion were essentially the same in each case. The calcium ionophore A23187 increased the rate of 45Ca uptake by motile zoospores, incubated in 100 microM CaCl2, but did not induce encystment under these conditions. The ionophore did not induce 45Ca efflux from pre-labeled zoospores. Incubation in EGTA and in K+ failed to induce either encystment or 45Ca excretion. We conclude that rapid excretion of a significant proportion of the zoospore calcium is linked to the early stage of stimulus-induced encystment, and that this comes from an intracellularly located, non-cytoplasmic source, such as the peripheral vesicles, but that changes in cellular Ca2+ are not necessarily the single controlling factor in the induction of encystment.

Hyperadrenalism in childhood and adolescence

Hyperadrenalism in childhood and adolescence has unique features that influence diagnosis and management. We reviewed our experience with 18 patients, ranging in age from 18 months to 18 years. Nine had bilateral adrenal hyperplasia, eight had adrenal neoplasms, and one had micronodular hyperplasia. Patients with congenital adrenal hyperplasia and hyperaldosteronism were excluded. Six patients with Cushing's disease diagnosed in earlier years were treated by total adrenalectomy and recently two patients underwent transsphenoidal removal of pituitary tumors. Bilateral adrenalectomy was carried out in one patient with micronodular hyperplasia and in a second because of elevated adrenocorticotrophic hormone (ACTH) levels from an undefined source. Eight patients had adrenal neoplasms, including five adenomas and three carcinomas. We found no reliable criteria to differentiate before surgery between adrenal adenomas and adrenal carcinomas. The most recognizable characteristic of malignancy was tumor size, specifically weight greater than 75 gms. Of the three patients with adrenal carcinoma, one expired 20 months after adrenalectomy and 8 months after receiving palliative partial hepatectomy for liver metastasis. Two patients are well with normal growth and development at 11 and 20 years following adrenalectomy. With the exception of one patient who died 6 years after surgery from a glioblastoma multiforme, all patients with adrenal adenomas are well. Eight patients underwent bilateral adrenalectomy for hypercortisolism. Five of the six who have reached their adult stature are significantly stunted. Four of six patients with Cushing's disease, treated by total adrenalectomy, have developed Nelson's syndrome at 2, 6, 10, and 12 years after surgery. Of the two patients undergoing transsphenoidal surgery, one had recurrent disease at 2 years and was treated by pituitary irradiation with recovery. The patients undergoing adrenalectomy for micronodular hyperplasia and ectopic ACTH are well at 2 and 4 years, respectively. Cushing's disease in children and adolescents is best treated by transsphenoidal removal of the pituitary adenoma. Adrenalectomy, once the most accepted approach, plays a secondary role and is indicated primarily in micronodular adrenal hyperplasia, in patients with ectopic ACTH production of an undefined source, and in recurrent Cushing's disease following prior pituitary irradiation. The high incidence of Nelson's syndrome in children treated by adrenalectomy mandates that patients at risk be monitored lifelong for the progression of a pituitary tumor.(ABSTRACT TRUNCATED AT 400 WORDS)

An ultrasound system for combined cardiac imaging and Doppler blood flow measurement in man

An ultrasound instrument has been developed that combines a real-time cross-sectional imaging system and a spectrum analyzer-based Doppler velocimeter. This combination allows the Doppler sample volume to be superimposed on the cross-sectional image of the heart so that the sample volume can be located accurately. The same 2.2 MHz transducer utilized for cross-sectional imaging is stopped mechanically and quickly switched to transmit and receive the Doppler ultrasound signal. Preliminary experience in 20 young and adult normal subjects indicates that it is possible to place the Doppler sample volume in the proximal main pulmonary artery at a point where the sound beam and blood flow stream are parallel. Measurement of the distance from transducer to the sample volume and the peak blood flow velocities in the main pulmonary artery of normal subjects indicates that these quantities are within the measurement capabilities of the system. The ultimate goal of this device is to make measurements of volume blood flow in man noninvasively.

Cross-sectional echocardiography in the diagnosis of congenital heart disease. Identification of the relation of the ventricles and great arteries

Using a mechanical sector-scanner, two-dimensional echocardiograms were obtained from 28 normal subjects, 15 patients with tetralogy of Fallot, 11 patients with complete transposition of the great arteries and six patients with double outlet right ventricle. The image obtained perpendicular to the long axis of the left ventricle at the base of the venticular septum was superimposed on the image obtained perpendicular to the long axis at the origin of the great arteries. In normal subjects, these superimposed images demonstrated that the aorta originated posterior and to the left of the ventricular septum. In patients with tetralogy of Fallot, the aorta was displaced anterior and to the right resulting in the aorta over-riding the ventricular septum. In patients with double outlet right ventricle both great arteries originated anterior to the ventricular septum (i.e., from the right ventricle). In patients with complete transposition, the aorta originated anterior and the pulmonary artery posterior to the ventricular septum. Thus, cross-sectional echocardiography permits noninvasive identification of the relation of the ventricles and great arteries and, therefore, provides important information for the diagnosis of patients with congenital heart disease.

The pulsed Doppler ultrasound flowmeter: experimental evaluation of velocity accuracy and range resolution

Accurate quantitation of blood flow patterns, particularly in the physiological state, is important to the successful study of several problems in biomedical research. The pulsed Doppler ultrasonic flowmeter offers promise of overcoming some of the difficulties present in other methods. This flowmeter can be either implantable or noninvasive. Although a number of papers describe important design criteria, the design or selection of a Doppler system for a given task remains a complex matter involving many compromises based on theoretical considerations and very limited data. Experimental data from well-defined flows are needed to help identify those areas in which ultrasonic flowmeters can be most useful. This paper defines and evaluates two important parameters for the pulsed Doppler ultrasonic flowmeter by comparing experimental results with those predicted theorectically. The first parameter is velocity accuracy; the second parameter is range resolution. Findings show that centerline flow velocities in circular tubes can be estimated to within a few percent of the correct value, and that a 1.5-mm range resolution can be realized with the system tested.

Regional contractility. Selective depression of ischemic myocardium by verapamil

The effects of verapamil (0.02-0.2 mg/kg) on contractility in normal and partially ischemic myocardium were compared with the changes following propranolol (0.01-1.0 mg/kg). Regional contractile function was studied in open-chest dogs with ultrasonic crystals and ischemia was controlled by graded occlusion of a carotid-to-coronary artery shunt. Reduction in shunt perfusion pressure (40-55 mm Hg) resulted in hypokinesia. Verapamil depressed contractility in ischemic myocardium in 5/5 dogs, but did not alter the maximum velocity of shortening (max V) or end-diastolic segment length in normal myocardium. Propranolol in doses sufficient to depress ischemic myocardium also depressed contractile function in normal myocardium. In two dogs without coronary occlusion, verapamil (up to 1.0 mg/kg) increased end-diastolic segment length but did not reduce max V. We conclude that verapamil selectively depresses ischemic myocardium, a finding that may have clinical implication since ischemic injury can be decreased by reducing contractility (and thereby MVO2).

Identification of congenital malformations of the great arteries in infants by real-time two-dimensional echocardiography

Real-time, two dimensional echocardiography was used to identify great artery relations in 23 infants and small children, including 16 patients with angiography documented transposition of the great arteries, tetralogy of Fallot, or pulmonary aresia. Using this technique, the heart was scanned perpendicular to its long axis at the origin of the great arteries. Great arteries cross-sectioned perpendicular to their long axes appear as circles; when sectioned longitudinally these arteries appeared as elongated sausage-shaped structures. I- patients with normally related great arteries, a curcular structure (aorta) always was positioned posterior to an elongated, sausage-shaped structure (distal right ventricular outflow tract and proximal main pulmonary artery). In transposition of the great arteries, two adjacent circular structures were observed; the anterior circle (aorta) was located to the right, left or directly anterior to the posterior circle (pulmonary artery). In pulmonary atresia or hypoplasis, a large posterior circle (aorta) was associated with an anteriorly positioned structure that was either short and small (atretic right ventricular outflow tract) or elongated with an area of severe narrowing (hypoplastic right ventricular outflow tract). Thus, real-time two-dimensional echocardiography provides a rapid, noninvasive means of accurately identifying congenital malformations of the great arteries in infants and small children and may be a useful adjunct to cardiac catheterization in the diagnosis of cyanotic congenital heart disease.

Measurement of mitral orifice area in patients with mitral valve disease by real-time, two-dimensional echocardiography

A quantitative assessment of mitral valve orifice area can be achieved in patients with pure mitral stenosis by cardiac catheterization. In the presence of mitral regurgitation, however, accurate measurement often is impossible because total diastolic flow through the mitral valve frequently is unknow. Using a recently developed real-time, two-dimensional echocardiography system, we are able to obtain cross-sectional images of the mitral valve by scanning the heart perpendicular to its long axis at the level of the tip of the mitral leaflets. Twenty consecutive patients undergoing operation for mitral valve disease were studied during the week prior to operation. In 18 of 20 (90%) the mitral orifice was imaged successfully in early diastole by two-dimensional echocardiography so that mitral valve orifice area could be measured directly in square centimeters. In 14 patients (ten with associated mitral regurgitation), mitral orifice area was measured both by echocardiography and directly at time of operation. In 12 of 14 (86%) patients, mitral orifice area by two-dimensional echocardiography was within 0.3 square centimeters of that measured at operation (correlation coefficient for all 14 patients equals 0.92). We conclude that two-dimensional echocardiography is extremely useful in the evaluation of patients with mitral valve disease because it provides a noninvasive method for directly measuring the mitral valve orifice area that is accurate even in the presence of mitral regurgitation.

Mechanism of left ventricular outlfow obstruction in patients with obstructive asymmetric septal hypertrophy (idiopathic hypertrophic subaortic stenosis)

Left ventricular outflow obstruction in patients with idiopathic hypertrophic subaortic stenosis or obstructive asymmetric septal hypertrophy is due to abnormal forward motion during systole of the anterior mitral leaflet. To determine why some patients with this disease hav left ventricular outflow obstruction whereas others do not, we studied a large number of patiens with assymetric septal hypertrophy using both one- and two-dimensional echocardiography. In 100 patients with asymmetric septal hypertrophy and 22 normal subjects, mitral valve position at the onset of systole was quantitated by measuring the distance from the ventricular septum to the mitral valve and the distance from the mitral valve to the posterior left ventricular wall. None of the normal subjects and only 3 (6 percent) of 51 patients with nonobstructive asymmetric septal hypertrophy had a septal-mitral valve distance of less than 20 mm compared with 23 (66 percent) of 35 patients with obstructive asymmetric septal hypertrophy. Moreover, the mitral valve at the onset of systole was actually positioned forward in the left ventricular activity. Two-dimensional studies in 11 patients with obstructive asymmetric septal hypertrophy revealed that contraction of the malaligned papillary muscles did not cause the abnormal forward mitral valve motion. We propose that the left ventricular outflow obstruction in patients with obstructive asymmetric septal hypertrophy occurs as a result of two factors: (1) narrowing of the left ventricular outflow tract at the onset of systole, and (2) hydrodynamic forces generated by contraction on the left ventricle.

A sector scanner for real time two-dimensional echocardiography

During the past several years one-dimensional pulse-echo ultrasound techniques have proven extremely useful in cardiac diagnosis. A one-dimensional system, however, only visualizes structures lying along a single straight line. The spatial relationships of the various cardiac structures are therefore not so easily defined as with two-dimensional systems which display the heart by constructing a plane image composed of many straight lines. We have developed a sector scanning system for obtaining two-dimensional echocardiograms in real time using ultrasonic pulse-echo techniques. Images are produced by angling rapidly a single transducer through a 30-degree sector from a fixed spot (between ribs) on the patient's chest. Thirty complete sectors (or frames) are produced per second. The use of a large diameter transducer ensures that signal strength is good and cardiac structures, including endocardium, can be visualized. Other advantages include high transducer sensitivity, real time imaging and easy visualization of various regions of the heart. Experience with more than 100 patients indicates that diagnostic quality two-dimensional echocardiograms can be readily obtained in essentially the same patients from whom one-dimensional echocardiograms are recorded and can usually be performed in less time.