The G alpha i homologue gna-1 controls multiple differentiation pathways in Neurospora crassa.

Heterotrimeric G proteins are components of principal signaling pathways in eukaryotes. In higher organisms, alpha subunits of G proteins have been divided into four families, Gi, Gs, Gq, and G12. We previously identified a G alpha i homologue gna-1 in the filamentous fungus Neurospora crassa. Now we report that deletion of gna-1 leads to multiple phenotypes during the vegetative and sexual cycles in N. crassa. On solid medium, delta gna-1 strains have a slower rate of hyphal apical extension than wild type, a rate that is more pronounced under hyperosmotic conditions or in the presence of a cellophane overlay. delta gna-1 mutants accumulate less mass than wild-type strains, and their mass accumulation is not affected in the same way by exposure to light. delta gna-1 strains are defective in macroconidiation, possessing aerial hyphae that are shorter, contain abnormal swellings, and differentiate adherent macroconidia. During the sexual cycle, delta gna-1 strains are fertile as males. However, the mutants are female-sterile, producing small, aberrant female reproductive structures. After fertilization, delta gna-1 female structures do not enlarge and develop normally, and no sexual spores are produced. Thus, mutation of gna-1 results in sex-specific loss of fertility.

Overlapping functions for two G protein alpha subunits in Neurospora crassa.

Heterotrimeric G proteins, consisting of alpha, beta and gamma subunits, mediate a variety of signaling pathways in eukaryotes. We have previously identified two genes, gna-1 and gna-2, that encode G protein alpha subunits in the filamentous fungus Neurospora crassa. Mutation of gna-1 results in female infertility and sensitivity to hyperosmotic media. In this study, we investigate the expression and functions of gna-2. Results from Western analysis and measurements of gna-2 promoter-lacZ fusion activity indicate that gna-2 is expressed during the vegetative and sexual cycle of N. crassa in both A and a mating types. Activating mutations predicted to abolish the GTPase activity of GNA-2 cause subtle defects in aerial hyphae formation and conidial germination. Extensive phenotypic analysis of delta gna-2 strains did not reveal abnormalities during vegetative or sexual development. In contrast, deletion of gna-2 in a delta gna-1 strain accentuates the delta gna-1 phenotypes. delta gna-1 delta gna-2 strains have a slower rate of hyphal apical extension than delta gna-1 strains on hyperosmotic media. Moreover, delta gna-1 delta gna-2 mutants have more pronounced defects in female fertility than delta gna-1 strains. We propose that gna-1 and gna-2 have overlapping functions and may constitute a gene family. This is the first report of G protein alpha subunits with overlapping functions in eukaryotic microbes.

What is marrow fibrosis after treatment of neuroblastoma?

AIMS: To test the hypothesis that the abnormal fibrous stroma of bone marrow found after treatment of disseminated neuroblastoma represents traumatic scarring. METHODS: Twenty six restaging bone marrow biopsy specimens from 14 children with disseminated neuroblastoma were compared with 37 from 37 children with acute lymphoblastic leukaemia. They were assessed independently by two observers for the presence of abnormal fibrous stroma. All biopsies were performed 23 to 50 days after the initial diagnostic biopsy, and from the same iliac crest. A further nine restaging bone marrow biopsy specimens from previously unbiopsied iliac crests from four children with neuroblastoma were examined and the appearances of the diagnostic bone marrow specimens in those with neuroblastoma recorded. Between diagnostic and restaging biopsies, the children received combination chemotherapy regimens. RESULTS: In neuroblastoma abnormal stromal material was observed in 17 of 26 rebiopsied iliac crests as opposed to only 9 of 37 of those with acute lymphoblastic leukaemia (p < 0.005). In addition, four of nine restaging biopsy specimens taken from previously unbiopsied crests in patients with neuroblastoma contained abnormal stroma. All 11 children with neuroblastoma whose restaging specimens contained abnormal stroma had similar abnormalities in one or more biopsy specimens at diagnosis. CONCLUSIONS: Abnormal fibrous stromal material in restaging marrow biopsy specimens of previously biopsied iliac crests occurs much more frequently in neuroblastoma than in acute lymphoblastic leukaemia. We suggest that factors other than traumatic scarring are responsible. This is supported by finding similar abnormalities in previously unbiopsied iliac crests and in the diagnostic biopsy specimens of children with neuroblastoma.

Resolution of chronic severe refractory thrombocytopenia after treatment of hypothyroidism.

The case of a 52 year old woman with chronic severe refractory thrombocytopenia is presented. Over a three year period, her platelet count was persistently less than 20 x 10(9)/litre (normal range, 150-400). She required repeated hospital admission for management of bleeding and received multiple blood transfusions. She was given repeated courses of steroids, immunosuppression, immunoglobulin, and splenectomy, without success, in an attempt to stop the chronic blood loss. Eventually, she was found to be profoundly hypothyroid. On correction of her thyroid deficiency the platelet count returned to the normal range and all bleeding stopped. The platelet count remains in the normal range three years later.

MR screening for brain stem compression in hypertension.

PURPOSE: To determine the clinical usefulness of MR imaging to screen for vascular compression of the lateral medulla, considered by some to be responsible for neurogenic hypertension. METHODS: MR images and clinical records of 120 adults who had received brain MR imaging for any reason were divided into two groups: group 1 (n = 60) consisted of patients with essential hypertension and group 2 (n = 60) included patients who lacked a diagnosis of hypertension. No patient manifested symptomatic cranial neuralgias. The root entry zone of cranial nerves IX and X into the left lateral medulla was examined by MR imaging for proximity to the ipsilateral vertebral artery or its branches. Images lacking any contact between visible vascular structures and the root entry zone were recorded as normal. Vascular compression was graded according to the degree of proximity to the root entry zone. Lateral medullary contact only (grade I), contact and depression (grade II), or lower brain stem displacement or rotation (grade III) of the root entry zone were recorded in both hypertensive and normotensive patients. Among hypertensive patients, additional data were gathered from electrocardiographic, echocardiographic, and urinary protein reports. RESULTS: We found compression in 34 (57%) of the patients from group 1 and in 33 (55%) of the patients from group 2. Compressions in group 1 were grade I in 22 (37%) of the patients, grade II in 8 (45%), grade II in 4 (7%), and grade III in 2 (3%). There were no statistically significant differences in MR findings between the two groups. Among group 1 patients, MR grading did not predict end-organ changes in the heart (left axis deviation and left ventricular hypertrophy) or kidneys (proteinuria). CONCLUSION: Vascular compression of the root entry zone of cranial nerves IX and X into the left lateral medulla is not an adequate lesion to produce systemic hypertension. This finding is as common among normotensive patients as among hypertensive populations. Neither the presence nor the severity of changes in the root entry zone on MR images increases the occurrence of common end-organ responses in the heart or kidneys among hypertensive patients. MR screening is not warranted among hypertensive patients lacking symptomatic cranial neuralgias.

Transdural spinal cord herniation: imaging and clinical spectra.

PURPOSE: Transdural herniation of the spinal cord is a rarely reported clinical entity, and many of the existing reports were published before the advent of MR imaging. We describe five current cases and compare them with findings in 25 cases reported in the literature to delineate the clinical and imaging spectra of transdural spinal cord herniation. METHODS: MR imaging, CT myelography, and conventional myelography were performed in five patients with transdural herniation of the spinal cord. These studies, along with clinical findings, are described. Intraoperative photographs are included for one case. The salient features of both the current and previously reported cases are summarized in tabular form. RESULTS: In three cases, transdural spinal cord herniation occurred posttraumatically, in one case the cause was iatrogenic and in the others the herniation occurred spontaneously. Imaging features not previously reported include dorsally directed herniations at thoracolumbar levels (two patients), apparent (lacking surgical confirmation) syringomeyelia (one case), a vertebral body nuclear trail sign (one case), and intramedullary hyperintensities on MR images (two cases). Clinical features not previously reported include unilateral pyramidal-sensory deficits (one case) and isolated unilateral pyramidal signs (one case). Clinical findings similar to previous reports include progressive paraparesis (two cases) and progressive Brown-Séquard syndrome (one case). CONCLUSION: Our five cases illustrate certain clinical and imaging findings not previously reported, and, together with the established features of the 25 cases in the literature, delineate the spectra of transdural spinal cord herniation.

Peer-group association and adolescent tobacco use.

Mosbach & Leventhal (1988) examined the relation of cigarette smoking to peer-group identification in rural Wisconsin adolescents. They found that among dirts (problem-prone youth), regulars (average youth), hot-shots (good social or academic performers), and jocks (athletes), youth most likely to smoke were dirts and hot-shots. We performed a replication with a Southern California cohort and also for use of smokeless tobacco. We hypothesized that jocks would be the main users of smokeless tobacco. We identified the same groups and an additional one, skaters (skateboarders or surfers). As Mosbach & Leventhal found, cigarettes were used most by dirts. Contrary to their results, but consistent with other research, we found that hot-shots were least likely to smoke. Contrary to our prediction, we found that skaters and dirts were more likely to use smokeless tobacco than were jocks. Our data show that both tobacco forms are used by problem-prone youth.

From early to late adolescence: alcohol use and anger relationships.

PURPOSE: To evaluate the longitudinal relationship of alcohol use in early adolescence to anger in late adolescence. METHODS: Data were collected in Indianapolis, Indiana, from 1987 to 1993 as part of a large drug abuse prevention trial. Fifty percent of the 1201 students were female, 75%, white, and 69%, low socioeconomic status, who were surveyed in grades 6/7, 9/10, and 11/12. Subjects were asked four anger-related questions: "When I have a problem, I get mad at people," "When I have a problem, I do bad things or cause trouble," "When I have a problem, I say or do nasty things," and "I am a hotheaded person." Two additional items asked subjects to report the number of alcoholic drinks consumed and frequency of drunkenness in the past 30 days. Odds ratios (OR) were used to assess the predictive relationship of alcohol use in early adolescence to anger in late adolescence. RESULTS: Early use of alcohol increased the odds of later anger. Specifically, alcohol use in the past month in grade 6/7 increased the odds in grade 11/12 of saying or doing nasty things (OR = 8.23, p < .01), self-reported hotheadedness (OR = 9.72, p < .01), and high anger on a composite anger scale (OR = 4.84, p < .05). Drunkenness in the past month in grade 6/7 increased the odds of self-reported hotheadedness (OR = 6.17, p <.05) and high anger on the anger scale (OR = 3.20, p < .05) in grade 9/10 and doing something bad to cause trouble in grade 11/12 (OR = 24.97, p < .01). For subjects in grade 9/10, alcohol use in the past month increased the odds in grade 11/12 of doing something bad to cause trouble (OR = 2.79, p < .05), saying or doing nasty things (OR = 2.02, p < .05), and self-reported hotheadedness (OR = 2.51, p < .05). CONCLUSIONS: The present study showed that alcohol use in early adolescence was associated with increased anger, both in middle and late adolescence, controlling for gender, age, and socioeconomic status. The findings suggest that alcohol and drug prevention programs delivered in early adolescence may have the capacity to prevent risk for later anger and related violent behavior.

Effect of mouth opening on bite-force discrimination.

The purpose of this study was to determine whether different extents of mouth opening affect normal subjects' (N = 24; 12 women, 12 men) ability to discriminate differences in their interincisor bite force. Three mouth openings were selected including 50, 70, and 90 percent of maximum opening for each subject. Bite force was measured using a specially designed strain gauge scale which permitted subjects to monitor visually when their biting force equalled a preset resistance. Resistance forces of 500 and 1000 gm. were selected as standards. The procedure involved the use of a modified method of constant stimuli in which each subject was presented with a series of paired resistance settings, one at a time--the first resistance setting being the standard and the second resistance was the comparator. This paired-comparisons procedure was continued until the subjects' difference limen (DL) value (the threshold of discrimination between two forces) could be established. An analysis of variance yielded no significant differences in subjects' ability to discriminate bite force as a function of mouth opening.

Fluoroscopy and nasoendoscopy in designing palatal lift prostheses.

Prosthodontists frequently provide prostheses for the management of speech disorders related to palatopharyngeal dysfunction. Optimal prosthetic management of the palatopharyngeal port requires close interaction between the prosthodontist and speech pathologist in the use of videofluoroscopy and videonasoendoscopy for design, placement, and modification of the prosthesis. Function of the palatopharyngeal port during production of controlled samples of connected speech can be observed from multiview fluoroscopy, including lateral and frontal projections. Like fluoroscopy, nasoendoscopy can be used to observe and record function of the palatopharyngeal port during speech. This article provides an overview of the procedures suggested for diagnosing palatopharyngeal disorders. A method for designing and placing a prosthesis to aid in obturating the nasopharynx is also suggested.

Identification of a G protein alpha subunit from Neurospora crassa that is a member of the Gi family.

Heterotrimeric G proteins, consisting of alpha, beta, and gamma subunits, are implicated in major signal transduction pathways controlling a diversity of functions in eukaryotic organisms. In the filamentous fungus Neurospora crassa, G proteins are implicated in the regulation of several environmental responses. As a first step in studying the role of G proteins in these processes, we have cloned the genes for two alpha subunits, gna-1 and gna-2, from Neurospora. The genes are located on different chromosomes and are differentially regulated during asexual development. The encoded proteins (Gna-1 and Gna-2) are the same size as members of the Gi-alpha family (approximately 40 kDa). The Gna-1 protein sequence is 55% identical overall to members of the Gi family and contains the consensus sequences for ADP-ribosylation by pertussis toxin and incorporation of myristic acid, which are found in this group. These properties make Gna-1 the first identified microbial alpha subunit to be a member of any class. Furthermore, incubation of a N. crassa plasma membrane fraction with pertussis toxin results in ADP-ribosylation of a protein substrate which is the approximate size of Gna-1. The predicted Gna-2 protein sequence does not share a high degree of sequence identity with the Gi class. However, the coding region contains at least one intron in a position conserved in the Gi family. We propose that the Gi family of alpha subunits is ancient and during evolution may have first appeared in filamentous fungi.

Acetylglutamate synthase from Neurospora crassa: structure and regulation of expression.

A DNA clone which complemented an arg-14 mutation of Neurospora crassa was isolated by sib selection from a cosmid library (pMOcosX). Southern and restriction-fragment-length polymorphism (RFLP) analysis confirmed that the cloned DNA contained the arg-14 gene. The arg-14 gene was identified as the structural gene for acetylglutamate synthase by immunodepletion of enzyme activity with antibodies prepared against an arg-14 fusion protein and by the thermal instability of acetylglutamate synthase in a temperature-sensitive arg-14 mutant. The fungai acetylglutamate synthase has little sequence homology to its bacterial counterpart, unlike other arginine biosynthetic enzymes. Expression of the arg-14 gene is regulated by cross-pathway control similar to many amino acid biosynthetic genes. However, expression of acetylglutamate synthase occurs throughout the developmental growth cycle, unlike other arginine biosynthetic enzymes.

Detection of t(14;18) in British follicular lymphoma using cytogenetics, Southern blotting and the polymerase chain reaction.

Cytogenetics, Southern blotting and PCR were used to detect t(14;18) in 72 British patients with follicular lymphoma. The overall incidence of the translocation was 76%. Cytogenetics was the most successful technique, but 10-30% of translocations detected karyotypically were missed by molecular methods, presumably due to break-points falling outside the range of probes and primers used here. Reliance on molecular detection alone may considerably underestimate the incidence of t(14;18) and it is therefore essential to use the most comprehensive range of probes and primers available.

Free air in the cavernous sinus as an incidental finding.

Free air within the cavernous sinus was discovered incidentally on a computed tomographic (CT) scan. We suggest that air bubbles were introduced inadvertently when contrast material was injected just prior to CT scanning. On a repeat CT scan 16 days later, the air had disappeared.

Multiple forms of arginase are differentially expressed from a single locus in Neurospora crassa.

The Neurospora crassa catabolic enzyme, arginase (L-arginine amidinohydrolase, EC 3.5.3.1), exists in multiple forms. Multiple forms of arginase are found in many vertebrates, but this is the only reported example in a microbial organism. The two major forms are structurally similar with subunit sizes of 36 and 41 kDa, respectively. The larger form is produced by mycelia growing in arginine-supplemented medium. Both forms are localized in the cytosol. The structural gene for arginase, aga, has been cloned and sequenced; it contains a 358-codon open reading frame with three in-frame ATGs at the amino terminus. Mutagenesis of these ATGs revealed that the first ATG initiates the 41-kDa protein and the third ATG initiates the 36-kDa protein. Mutation of the second ATG has no effect on translation. Northern analysis demonstrated that a 1.4-kilobase (kb) transcript is synthesized in minimal medium and both a 1.4- and 1.7-kb transcript are produced in arginine-supplemented medium. Primer extension identified the 5' ends of each transcript and demonstrated that the first and third ATG of the open reading frame are the initial AUGs of the 1.7- and 1. 4-kb mRNA, respectively. The results suggest that a basal promoter produces the 1.4-kb transcript and an arginine "activated" promoter is responsible for the 1.7-kb transcript. Tandem promoters are rare in eukaryotic organisms, and they often regulate developmental or tissue-specific gene expression. The possibility that arginase has a role in differentiation in N. crassa is being investigated.

Intraoral air pressure discrimination under conditions of partial and complete resistance.

This study assessed a sample of normal-speaking individuals' ability to discriminate differences in their self-generated intraoral air pressures. Two conditions were employed: (1) open tube in which subjects had to sustain an expiratory breath stream to maintain the target pressure, and (2) closed tube in which there was complete resistance to the subjects' breath stream. Analysis of variance revealed no significant difference (p > 0.05) in subjects' ability to discriminate differences in their self-generated intraoral air pressure as a function of open or closed tube conditions. However, subjects' discrimination scores significantly increased (p < 0.05) as the standard pressure was increased.

Laparoscopic splenectomy: single-centre experience of a district general hospital.

We report the results of 20 consecutive laparoscopic splenectomies performed on haematology patients for a number of indications. Our series includes patients up to 77 years of age at the time of surgery and removal of spleens weighing up to 3530 g. The most significant benefit is the early rate of discharge post-operatively (median 2 d); however, there is a risk of conversion to open laparotomy (in this series 3/20, 15%). We show that laparoscopic splenectomy can be offered as a therapeutic option to patients unfit for conventional laparotomy and that even large and bulky spleens can be removed safely using this approach.

Human bite force discrimination using specific maxillary and mandibular teeth.

The purpose of this study was to determine whether performance differences existed in subjects' self-generated bite force discrimination ability using maxillary and mandibular central incisors, canines, premolars and first molars. Two separate studies were conducted: (i) to assess whether performance differences existed in subjects' bite force discrimination ability using central incisors and premolars; (ii) to compare subjects' performance on bite force discrimination using central incisors, canines and first molars. Assessment of bite force was measured using a specially designed strain gauge scale allowing subjects to visually monitor when their biting force equalled a preset resistance. Resistance forces of 500, 1000 and 3000 g were selected as standards. Subjects were presented with a series of paired resistance settings, one at a time, the first of each pair being the standard and the second being the comparator setting of a predetermined amount. This paired-comparisons procedure was continued until the subjects' difference limen (DL) value (the threshold of discrimination between two forces) could be established. The first study revealed no significant (P greater than 0.05) overall difference in subjects' bite force discrimination ability relative to specific teeth. In contrast, in the second study a significant difference (P less than 0.05) was identified in subjects' performance relative to specific teeth; subjects' performed better using central incisors compared to first molars. In both studies, subjects' performance was significantly better (P less than 0.05) using the 500 g standard compared to the 3000 g standard in the first study, and compared to the 1000 g standard in the second study. No significant differences (P greater than 0.05) were observed between the performance of males and females in either study.