Oscillations and multiple steady states in a cyclic gene model with repression

In this paper we study the cyclic gene model with repression considered by H. T. Banks and J. M. Mahaffy. Roughly, the model describes a biochemical feedback loop consisting of an integer number G of single gene reaction sequences in series. The model leads to a system of functional differential equations. We show that there is a qualitative difference in the dynamics between even and odd G if the feedback repression is sufficiently large. For even G, multiple stable steady states can coexist while for odd G, periodic orbits exist.

Hyperapobetalipoproteinemia in a kindred with familial combined hyperlipidemia and familial hypercholesterolemia

A child showed a type IIb lipoprotein pattern and triglyceride-enriched cutaneous xanthomas before 1 year of age. The proband and 9 of 18 relatives had elevated plasma levels of low density lipoprotein (LDL) B protein; of these nine relatives, four had elevated LDL of increased density while five had elevated LDL of normal density. Compared with normal LDL, LDL of increased density had less cholesteryl ester and free cholesterol, more apolipoprotein B and triglyceride, and a lower molecular weight and flotation rate (Sf degrees). Patients with LDL of increased density had higher mean plasma levels of triglycerides, very low density lipoproteins, and intermediate density lipoproteins, but lower levels of high density lipoproteins than those with elevated LDL of normal density. Multiple lipoprotein patterns in the father's family suggested the presence of familial combined hyperlipidemia (FCH). The mother of the proband and two of her relatives had type IIa lipoprotein patterns and tendon xanthomas, compatible with familial hypercholesterolemia (FH). High affinity binding, internalization, and degradation of 125I LDL in cultured fibroblasts from the proband and his mother were reduced two- to threefold compared with normal cells, while LDL receptor activity in the proband's father was normal. This unusual proband has apparently inherited both FCH and FH.

Indication of thioglucosidase activity in extracts of Neisseria gonorrhoeae

The recent demonstration of a host-derived inducer of gonococcal resistance to complement-mediated killing by human serum in purified serum and red blood cell fractions, which contained small glucopeptides with cysteine as one of the constituent amino acids, prompted an investigation of Neisseria gonorrhoeae for thioglucosidase activity. This involved an examination of supernatants of sonicated gonococci for thioglucoside hydrolysis by following, spectroscopically, the hydrolysis of 6-purine beta-D-glucothiopyranoside to 6-mercaptopurine and glucose. Extracts of N. gonorrhoeae were found to hydrolyse this thioglucoside. A substantial activity was present in a fraction with the same order of molecular weight as plant thioglucosidases. This led us to suspect the presence of a thioglucosidase in N. gonorrhoeae.

Immature circulating lymphocytes in severely malnourished Guatemalan children

The percentage of peripheral blood lymphocytes forming rosettes with sheep erythrocytes (E-rosettes) was determined in 33 severely malnourished Guatemalan children, and in two groups of clinically well but mildly growth retarded children from the same environment. Mean E-rosettes in the acutely ill patients was lower than the value observed in the mildly malnourished children, although there was considerable overlap between groups. These data differ from previously published studies of severely malnourished children from other parts of the world in that not all patients had decreased values for E-rosettes, in contrast to the uniform depression reported by others. As all patients were clinically similar, the results suggest that there may be specific nutrient defects associated with protein-energy malnutrition that particularly affect immune function. In addition, in vitro incubation of lymphocytes from the acutely malnourished children with the thymic factor, thymosin fraction 5, increased the percentage of E-rosettes in a dose-dependent fashion. These data suggest that immature, thymosin-responsive T cells are present in circulation. It is possible that in vivo thymosin administration may be beneficial for malnourished individuals.

Acute myelopathy associated with primary infection with human immunodeficiency virus

A 29 year old white homosexual man presented with a two and a half week history of severe sore throat, fever, and extreme fatigue. His symptoms did not respond to antibiotics. He had mild bilateral conjunctivitis, a rash over his chest and back, and enlarged lymph nodes, but examination of the nervous system yielded normal results. He had low total white cell and platelet counts. The results of enzyme linked immunosorbent assay for human immunodeficiency virus (HIV) were equivocal when HIV IgM was detected in serum. Despite treatment with ampicillin his temperature remained high and he developed abnormal neurological signs, including a paraparesis and hyperreflexia of the arms. HIV was isolated from lymphocytes from blood and cerebrospinal fluid. Over the next six weeks the patient improved and was discharged. Two months later abnormal neurological signs persisted in his legs. Although various neurological syndromes associated with seroconversion to HIV have been described, this is probably the first report of a patient with myelopathy at the time of seroconversion.

Airway hyper-reactivity and eosinophilia in rats treated with Sephadex particles

The intravenous injection of Sephadex particles (G200) into rats produced a specific increase in numbers of blood eosinophils, peaking 7 days later. A second injection, given on day 14 when the numbers of blood eosinophils had fallen to control levels, produced a dose-dependent increase in numbers, greater than the first, and peaking 5 days later. At this time, there was a dose-dependent increase in numbers of eosinophils, but not of other leucocytes, in broncho-alveolar lavage fluids and lung tissue, together with an increase in sensitivity of the rats to the respiratory effects produced by the intravenous injection of 5-hydroxytryptamine.

Clinical evaluation of a two-site immunoradiometric assay for adrenocorticotrophin in unextracted human plasma using monoclonal antibodies

We have developed a sensitive two-site immunoradiometric assay (IRMA) for intact ACTH and its precursors, pro-opiomelanocortin and 22 kDa peptide in unextracted human plasma. The assay uses two monoclonal antibodies. Antibody 1A12, specific for ACTH 10-18, is radiolabelled and antibody 2A3 specific for the C-terminal region (ACTH 24-39), is coupled to Sephacryl S300 for the solid-phase. Samples are incubated for 18 h with labelled antibody followed by 2 h with solid-phase antibody. Separation employs the sucrose layering technique. Using human pituitary ACTH 1-39 (code 74/555) in diluent containing 10% horse serum to standardize the assay, the sensitivity (upper 99% confidence limit of zero standard) is 3.5 +/- 0.8 ng/l (n - 7). The mean coefficient of variation is 5.9% within-assay and 6.7% between-assay and is less than 10% between 22 and greater than 5000 ng/l. Mean recovery of ACTH 1-39 added to dexamethasone-suppressed human plasma is 109% and endogenous ACTH behaves indistinguishably from standard ACTH on dilution. In normal subjects, mean plasma ACTH levels are 30 ng/l at 0730 h, and 15 ng/l at 1630 h at rest. ACTH concentrations are between 60 and 330 ng/l, 8-10.5 h after metyrapone (2 g orally at 2300 h), between 140 and 320 ng/l, 30-60 min after insulin-induced hypoglycaemia, and less than 4 ng/l, 8 h after dexamethasone (1.5 mg orally at 2300 h). In a range of pathological conditions ACTH concentrations accurately reflect the disorders of the pituitary-adrenal axis. Endogenous ACTH immunoactivity is stable in vitro at 22 degrees C for at least 1 h in whole blood and at least 4 h in plasma. It is concluded that this two-site IRMA for ACTH in unextracted plasma offers a reliable assay for clinical purposes.

Production of passive immunity in neonatal ferrets following maternal vaccination with killed influenza A virus vaccines

Neonatal ferrets may be passively immunized following maternal vaccination with formalin-inactivated influenza A virus vaccine, but the level of protection from partial to complete depends upon the number of doses used to vaccinate the mother, the presence or absence of aluminum hydroxide adjuvant, whether or not the mothers were 'primed' by prior infection with a serologically heterologous type A virus, and the age of the neonate at challenge. Neonates were completely protected up to 2 weeks of age, but susceptibility returned to nasal epithelium at 5 weeks and to lung at 7 weeks. Mothers immunized up to 9 months previously also partially or completely protected their offspring, this correlating with the maternal serum haemagglutination-inhibition (HI) antibody titre at the time of neonatal challenge, not the duration of immunity.

Aspergillus nidulans beta-tubulin genes are unusually divergent

Aspergillus nidulans has two beta-tubulin genes: benA, which is involved in both vegetative growth and asexual sporulation, and tubC, which is involved mainly in asexual sporulation. Both genes have now been cloned and sequenced. benA encodes a polypeptide of 447 amino acids (aa) and tubC encodes one of 449 aa. The two polypeptides differ by 78 aa residues but the net charge for the two proteins remains the same. The divergence between the amino acid sequences of the Aspergillus beta-tubulins is greater than that for any other two beta-tubulins yet described in the same organism. The benA gene has eight introns and the tubC gene has five, all of which correspond in amino acid position to introns in benA. The positions of some of these introns are conserved in other beta-tubulin genes. The 5'-splice site, internal, and 3'-splice site consensus sequences are similar to those found in other fungal introns. The transcriptional start points for each gene have been determined using primer extension and/or S1 nuclease mapping. Neither the benA gene nor the tubC gene contains a TATA sequence in its 5'-flanking region. The tubC gene has two repeated upstream sequences which are not found in benA. The sites of polyadenylation have been determined for each gene using S1 nuclease mapping. Neither gene contains a polyadenylation signal, AATAAA, typical of other eukaryotic genes.

Clinical features of covert toxocariasis

The clinical features found in 14 children with toxocara ELISA titres of greater than or equal to 0.7 were compared with those found in 34 toxocara negative children. Blood eosinophils were elevated in 7 of the 14 patients and the highest eosinophilia was 14%. There was a highly significant association between hepatomegaly, cough, sleep disturbance and a raised titre (p less than 0.01). Behaviour disturbance, abdominal pain and headache were also significantly associated with a raised titre (p less than 0.05). The combination of abdominal pain, headache and cough was even more significantly associated with a high titre (p less than 0.0005) than were individual clinical features. It is suggested that in addition to the two well recognised clinical conditions of visceral larva migrans and ocular toxocariasis the clinical entity of covert toxocariasis should receive recognition. Eosinophilia may or may not be present in this condition.

Gonococci in vivo and in vitro. Further studies on the host and bacterial determinants of gonococcal resistance to killing by human serum, and by phagocytes

A small M, heat and acid labile, host inducer(s) of gonococcal resistance to complement mediated killing by fresh human serum (-FHS), being purified from red blood cell (RBC) extracts, produced changed in lipopolysaccharide (LPS) structure, surface antigens and proteins; and acquirement of resistance related to loss of a target antigen for bactericidal IgM, possibly LPS components. A 20 kDalt. lipoprotein with a high content of glutamic acid isolated from outer membranes of a gonococcal strain selected in vivo is a determinant of gonococcal resistance to killing by human phagocytes. Sonic extracts of gonococci may contain a cytotoxin for human phagocytes. At the 4th International Pathogenic Neisseriae Conference, we reported (Parsons et al. 1985) that conditions in vivo induced phenotypic change leading to gonococcal resistance to complement-mediated killing by human serum; and, also, selected gonococcal types which showed a greater resistance to intracellular killing by human phagocytes than laboratory strains. Furthermore, evidence was presented that not only was resistance to complement mediated killing important in gonococcal pathogenesis, but also resistance to phagocytic defences. This paper describes the continuance of our studies on the determinants of induced serum resistance and of resistance to killing by phagocytes including toxicity to these cells. Each section begins by summarising previous work that was referenced in Parsons et al. (1985).

The differential impact of diabetes type on female sexuality

Although diabetes is associated with a high prevalence of erectile impairment in men, its effect on the sexuality of women remains unclear. Since diabetes consists of different disorders, diabetes type may have confounded previous studies by differentially impacting on sexual functioning and marital satisfaction. To evaluate this possibility, 35 Type I diabetic married women were compared with 42 healthy married controls and 23 Type II diabetic women with 23 controls. Assessments were made on all aspects of sexual response, activity, dysfunction and satisfaction; on cognitive and psychological dimensions of sexuality; and on marital adjustment. Results indicated that diabetes type is highly associated with sexual responsiveness and marital satisfaction. Type I diabetes was found to have little or no effect on women, while Type II diabetes had a pervasively negative impact on sexual desire, orgasmic capacity, lubrication, sexual satisfaction, sexual activity, and on the relationship with the sexual partner.

Erythrocytic sedimentation rate as a measure of clinical activity in inflammatory bowel disease

To assess the reliability of the erythrocytic sedimentation rate (ESR) as a measure of clinical activity in inflammatory bowel disease, we analyzed the correlations of ESR with a global assessment of clinical activity in 77 patients with varying extents of Crohn's disease and ulcerative colitis. Analysis of all 141 ESR determinations in all 77 patients showed a highly significant correlation between mean ESR and clinical activity score (r = 0.54, p less than 0.001). Analysis of 133 ESR determinations in these 77 patients when their disease activity was either mild, moderate, or severe showed some significant differences among certain disease categories. The highest mean ESRs were in patients with the most extensive colon involvement (Crohn's colitis 40.7 +/- 3.3, universal ulcerative colitis 31.0 +/- 3.9), whereas the lowest mean ESRs were in patients with the most limited disease (ulcerative proctitis and proctosigmoiditis 19.2 +/- 2.1). The rate of increase in ESR with progressively increasing clinical activity from mild to moderate was the same in all disease categories, with the exception of Crohn's disease limited to the small bowel (ileitis or jejunoileitis), in which the ESR was relatively unchanged in a small sample of patients. By the time clinical activity became severe, however, patients in all disease categories manifested similarly high ESRs, with the exception of ulcerative proctitis in which the ESR remained low in the single patient tested.(ABSTRACT TRUNCATED AT 250 WORDS)

A determinant of resistance of Neisseria gonorrhoeae to killing by human phagocytes: an outer membrane lipoprotein of about 20 kDa with a high content of glutamic acid

A protein of about 20 kDa was extracted by sodium cholate (1%, w/v) from outer membranes of a strain of Neisseria gonorrhoeae, BS4 (agar), which is resistant to killing by human phagocytes. When the protein was purified by repeated fractionation on Sephadex G75, contamination with other outer-membrane proteins and lipopolysaccharide was negligible. The protein contained a full complement of amino acids, with high levels of glutamic acid. Carbohydrate, detected by the anthrone method and by sugar and hexosamine analysis, was present, but at very low levels. There was a significant content of fatty acids (about 5.7% of the protein), indicating a lipoprotein. The 20 kDa lipoprotein: (1) neutralized the ability of antiserum against whole organisms of BS4 (agar) to reduce the resistance of this strain to phagocyte killing; (2) evoked in mice an antiserum which reduced this resistance and immunoblotted only with 20 kDa lipoprotein in the cholate extract of outer membranes; and (3) promoted resistance to intracellular killing of an otherwise phagocyte susceptible gonococcal strain (BSSH). This is strong evidence that it is a determinant of gonococcal resistance to phagocyte killing.

Plant regeneration and thebaine content of plants derived from callus culture of Papaver bracteatum

Plants have been regenerated from embryogenic callus cultures of two varieties of Papaver bracteatum and successfully transplanted to soil. Regeneration occurred in good yield, around 40 plants to soil within 5 months per 0.4g piece of original callus. Thebaine concentrations comparable to those in seed-grown plants were obtained in callus-derived plants. It is suggested that there is potential for mass micropropagation of P. bracteatum, which may be useful in developing agriculturally-improved lines.

Studies on 1,2,3-triazoles. 13. (Piperazinylalkoxy) [1]benzopyrano[2,3-d]-1,2,3-triazol-9(1H)-ones with combined H1-antihistamine and mast cell stabilizing properties

Several N-benzylpiperazino derivatives of [1]benzopyrano[2,3-d]-1,2,3-triazol-9(1H)-one and its 5-methyl homologue have been prepared and evaluated for H1-antihistamine activity on guinea pig ileum. The most potent compounds were also evaluated for their ability to stabilize mast cells in the rat passive peritoneal anaphylaxis (PPA) system and were shown to inhibit histamine release at concentrations below those required to inhibit extravasation, suggesting that this might be relevant to their antianaphylactic activity in this system. The compound tested with the most potent H1-antihistamine activity was 6-[3-[4-(4-chlorobenzyl)-1-piperazinyl]propoxy][1]benzopyrano[2,3- d]-1,2,3-triazol-9(1H)-one, 28, which had a pA2 of 9.1 against histamine on guinea pig ileum, comparable to that of mepyramine, and inhibited histamine release in the rat PPA system with an IC50 value of 5.4 X 10(-6) M.

Measurement of regional wall motion from biplane contrast ventriculograms: a comparison of the 30 degree right anterior oblique and 60 degree left anterior oblique projections in patients with acute myocardial infarction

The value of performing biplane vs single plane analysis of regional wall motion from contrast ventriculograms was determined in 102 patients who received thrombolytic therapy and who underwent biplane ventriculography during acute myocardial infarction (n = 67), at follow-up more than 2 weeks later (n = 80), or both (n = 45). Hypokinesis in the infarct region and hyperkinesis in the noninfarct region were measured by the centerline method in the respective artery territories, which were defined from the data of 62 patients with single-vessel disease and were expressed in units of standard deviations from the mean of 32 normal subjects. Hypokinesis was more severe and extended over a longer segment of the left ventricular contour when measured in the right anterior oblique (RAO) projection in thrombosis of the left anterior descending coronary artery (LAD) but more severe and extensive in the left anterior oblique (LAO) projection in circumflex stenosis. Hyperkinesis opposite the LAD or the circumflex was greater in the LAO projection. In patients with thrombosis of the right coronary artery, wall motion abnormalities were similar in the two projections. Thus the evaluation of hypokinesis caused by acute coronary thrombosis and of the effect of therapeutic interventions in salvaging function can be adequately evaluated from single-plane 30 degree RAO ventriculograms, except in the small minority of patients with circumflex thrombosis.

Dementia in idiopathic Parkinson's disease. Variables associated with its occurrence in 203 patients

A series of 203 patients with primary Parkinson's disease treated with L-DOPA, with adequate neurological documentation of mental status at serial intervals during their illness, constitutes the study population. Based on the results of the latest neurological examination, slightly less than one-third (29%) had mental impairment assessed as neurologically significant. Of the eleven clinical variables analysed (Cox regression analysis) for potential influence on the occurrence of an organic mental syndrome, four had a statistically significant effect: (1) the stage of disease at initial neurological examination; (2) the occurrence of acute confusional states; (3) the years of Parkinson's prior to L-DOPA; and (4) the total duration of L-DOPA therapy. The pathogenesis of dementia in this subgroup of Parkinson's disease is discussed.

Molecular studies of the differential replication at pyrexial temperatures of two influenza viruses differing in virulence for ferrets

Replication of a virulent clone (7a) of the reassortant influenza virus A/Puerto Rico/8/34-A/England/939/69 (H3N2) in ferret nasal turbinate tissue is less affected than that of an attenuated clone (64d) by temperatures which occur during pyrexia in ferrets. This is a factor which contributes to the difference in virulence of the two clones. The differential replication of the two clones at pyrexial temperatures has been reproduced in allantois-on-shell (egg-bit) cultures, and the synthesis of viral polypeptides and RNA species examined. This virus-host system was chosen because it was more convenient to use than organ cultures but, like the latter, might provide information relevant to the in vivo situation. With this system it was not possible to achieve single cycle replication: the observed effects are cumulative over several (2 to 3) cycles of replication (24 h) and therefore conclusions from them may not be as definitive as those from single cycle conditions. However, in cells infected with clone 64d both A(+) cRNA and polypeptide synthesis were little affected at 40 degrees C but levels were decreased by about 70-80% at 41 degrees C; A(+) cRNA and polypeptide levels were unaffected even at 41 degrees C with clone 7a. These reductions seem insufficient to account for the 10-fold reduction in infectious yields of clone 64d at 40 degrees C or the 100-fold and 10-fold reductions in yields of clones 64d and 7a respectively at 41 degrees C. There was no evidence of increased production of non-infectious virus at elevated temperatures by either clone. Levels of vRNA were considerably reduced at 40 and 41 degrees C for both clones, but the levels were considerably greater at all temperatures in clone 7a-infected cells than in those infected with clone 64d; vRNA levels were higher for clone 7a at 41 degrees C than for clone 64d at 37 degrees C. The different levels of vRNA do not reflect differences in the availability of template A(-) cRNAs since levels of these were similar for both clones at 37 and 40 degrees C and only reduced for clone 64d at 41 degrees C. Although the interpretation of these data is complicated by multiple cycles of replication it appears that limited availability of vRNA could be an important constraint on the ability of clone 64d to replicate at pyrexial temperatures.

Altered chromatin in childhood leukaemic lymphoblasts: association with virus-like particles

An electron microscopic examination was made of masses identified as altered heterochromatin in the cytoplasm of childhood leukaemic lymphoblasts, and their relation to 'virus-like' particles (VLP). The masses were found to occur more frequently in leukaemic lymphoblasts than in normal lymphocytes, but abnormally frequent occurrence was a feature of non T rather than T or B lymphoblasts. Although these masses may be derived by phagocytosis of dead cells or cellular material, a more likely origin is by detachment of altered portions of the containing cell's own nucleus. Such in situ alterations in nuclei were seen in leukaemic lymphoblasts but not in normal lymphocytes. A close relation demonstrated between altered chromatin and VLP might suggest that VLP are a response to the presence of damaged chromatin. However, the occurrence in some VLP of solid cores and budding might make it more likely that VLP are viral, with chromatin damage as a morphologically recognizable cytopathic effect of their activity.

Cerebral astrocytoma as a complication of acute lymphoblastic leukaemia

A boy who developed acute lymphoblastic leukaemia at the age of two years and 10 months had several central nervous system relapses, and received two courses of cranial irradiation, each of 24 Gy, in addition to systemic and intrathecal chemotherapy. Nearly 10 years after the onset of his leukaemia he developed a brain stem astrocytoma from which he died. This appears to be a rare occurrence, and the role of the treatment in the induction of his second tumour is discussed. The need for the long-term follow-up of cancer patients after apparent cure is emphasized.