The role of infectious agents in sudden infant death syndrome

Abstract Epidemiological factors associated with susceptibility to respiratory infections are similar to those associated with Sudden Infant Death Syndrome. Here we review the evidence that respiratory pathogens might be involved in some cases of Sudden Infact Death Syndrome in the context of factors identified in epidemiological studies of cot deaths: the age range affected; mother's smoking; respiratory viral infections; immunisation status. Both laboratory and epidimiological evidence suggests that vulnerability of infants to infectious agents depends on interactions between genetic, developmental and environmental factors that contribute to colonisation by microorganisms, the inflammatory and specific immune responses and the infants' physiological responses to inflammatory mediators. A model is proposed to explain how microorganisms might trigger a series of events resulting in some of these unexpected deaths and discusses how the present recommendations regarding child care practices might help reduce the numbers of Sudden Infant Death Syndrome cases associated with infectious agents.     

Detection of microbial surface antigens that bind Lewisa antigen

Abstract There is evidence that the Lewis^a blood group antigen is one of the receptors for a number of potentially pathogenic microorganisms. To determine how widely distributed the microbial adhesins are that bind this antigen, anti-idiotypic antibodies produced against monoclonal anti-Lewis^a were used in coagglutination assays to screen a variety of species. The following were agglutinated: 7/7 strains of Staphylococcus aureus ; 10/19 (53%) strains of Neisseria meningitidis ; 8/13 (62%) strains of Haemophilus influenzae ; 1/3 strains of Helicobacter pylori ; 1/2 strains of Neisseria gonorrhoeae ; 1/2 strains of Candida albicans . The application of the anti-idiotypic antibodies to studies of host cell receptors, isolation of adhesins and development of new epidemiological typing reagents is discussed.     

Evidence for the role of glycoprotein G of respiratory syncytial virus in binding of Neisseria meningitidis to HEp-2 cells

Abstract Viral glycoproteins G and F are expressed on the surface of cells infected with respiratory syncytial virus (RSV). We investigated the role of these proteins in the previously reported enhanced binding of Neisseria meningitidis to RSV-infected HEp-2 cells. Virus particles attached to bacteria were detected by immunofluorescence with flow cytometry. Binding of FITC-labelled bacteria to RSV-infected cells was significantly inhibited by monoclonal antibody against glycoprotein G. Unlabelled bacteria interfered with binding of the anti-G monoclonal antibody to these cells. These interactions were not found with a monoclonal antibody against glycoprotein F. We propose that glycoprotein G of RSV expressed on the surface of infected cells might act as an additional receptor for meningococci.     

An extensive review on antifungal approaches in the treatment of mucormycosis

During the period of COVID-19, the occurrences of mucormycosis in immunocompromised patients have increased significantly. Mucormycosis (black fungus) is a rare and rapidly progressing fungal infection associated with high mortality and morbidity in India as well as globally. The causative agents for this infection are collectively called mucoromycetes which are the members of the order Mucorales. The diagnosis of the infection needs to be performed as soon as the occurrence of clinical symptoms which differs with types of Mucorales infection. Imaging techniques magnetic resonance imaging or computed tomography scan, culture testing, and microscopy are the approaches for the diagnosis. After the diagnosis of the infection is confirmed, rapid action is needed for the treatment in the form of antifungal therapy or surgery depending upon the severity of the infection. Delaying in treatment declines the chances of survival. In antifungal therapy, there are two approaches first-line therapy (monotherapy) and combination therapy. Amphotericin B ( 1 ) and isavuconazole ( 2 ) are the drugs of choice for first-line therapy in the treatment of mucormycosis. Salvage therapy with posaconazole ( 3 ) and deferasirox ( 4 ) is another approach for patients who are not responsible for any other therapy. Adjunctive therapy is also used in the treatment of mucormycosis along with first-line therapy, which involves hyperbaric oxygen and cytokine therapy. There are some drugs like VT-1161 ( 5 ) and APX001A ( 6 ), Colistin, SCH 42427, and PC1244 that are under clinical trials. Despite all these approaches, none can be 100% successful in giving results. Therefore, new medications with favorable or little side effects are required for the treatment of mucormycosis.     

Antimicrobial effects of tea-tree oil and its major components on Staphylococcus aureus, Staph. epidermidis and Propionibacterium acnes

Major components of two tea-tree oil samples were identified using thin layer and gas-liquid chromatography (TLC and GLC). Using a TLC-bioautographic technique, the tea-tree oils, terpinen-4-ol, oc-terpineol and α-pinene were found to be active against Staphylococcus aureus, Staph. epidermidis and Propionibacterium acnes whereas cineole was inactive against these organisms. The MIC values of the three active compounds increased in the order α-terpineol < terpinen-4-ol < α-pinene for all three micro-organisms. MIC values of the tea-tree oils and terpinen-4-ol were lower for P. acnes than for the two staphylococci. This study supports the use of tea-tree oil in the treatment of acne, and demonstrates that terpinen-4-ol is not the sole active constituent of the oil.     

Is hyperglycaemia an independent predictor of poor outcome after acute stroke? Results of a long-term follow up study.

OBJECTIVE: To determine whether raised plasma glucose concentration independently influences outcome after acute stroke or is a stress response reflecting increased stroke severity. DESIGN: Long-term follow up study of patients admitted to an acute stroke unit. SETTING: Western Infirmary, Glasgow. SUBJECTS: 811 patients with acute stroke confirmed by computed tomography. Analysis was restricted to the 750 non-diabetic patients. MAIN OUTCOME MEASURES: Survival time and placement three months after stroke. RESULTS: 645 patients (86%) had ischaemic stroke and 105 patients (14%) haemorrhagic stroke. Cox''s proportional hazards modelling with stratification according to Oxfordshire Community Stroke Project categories identified increased age (relative hazard 1.36 per decade; 95% confidence interval 1.21 to 1.53), haemorrhagic stroke (relative hazard 1.67; 1.22 to 2.28), time to resolution of symptoms > 72 hours (relative hazard 2.15; 1.15 to 4.05), and hyperglycaemia (relative hazard 1.87; 1.43 to 2.45) as predictors of mortality. The effect of glucose concentration on survival was greatest in the first month. CONCLUSIONS: Plasma glucose concentration above 8 mmol/l after acute stroke predicts a poor prognosis after correcting for age, stroke severity, and stroke subtype. Raised plasma glucose concentration is therefore unlikely to be solely a stress response and should arguably be treated actively. A randomised trial is warranted.     

Effects of tumour necrosis factor-alpha on BrdU incorporation in cultured human enterocytes

Bromodeoxyuridine incorporation is a useful method for studying the pattern of DNA synthesis in proliferating cells. The distribution pattern of incorporated BrdU in villus enterocytes of duodenal explants was analysed after exposure to TNFalpha in organ culture. TNFalpha caused a consistent, low level uptake of BrdU in the portion of the nucleus close to the nuclear membrane, this pattern was absent from the control cultures. As these epithelial cells are terminally arrested in G(0), the BrdU incorporation was thought not to be due to S phase DNA synthesis, but rather a response to the cytotoxic influence of TNFalpha. Microtitre plate proliferation assays of cell density and DNA synthesis were devised to study the effects of TNFalpha on confluent monolayers of the human foetal jejunal cell line I407 and the mouse fibrosarcoma cell line L929. Both cell lines showed a similar response to TNFalpha. Exposure to TNFalpha alone did not reduce cell numbers but did cause a significant increase in DNA synthesis (p < 0.05). When cycloheximtde was added in tandem with TNFalpha there was a significant reduction in cell number (p < 0.001) and level of DNA synthesis (p < 0.01) indicative of cell death. The DNA of cells exposed to TNFalpha and cycloheximide was fragmented when viewed on an electrophoresis gel. The results show that BrdU incorporation might be a good indicator of damage to the DNA of cells after cytotoxic insult. TNFalpha may be responsible for villus enterocyte damage in enteropathies such as coeliac disease and GVHR of the small bowel.     

Effect of Mating Structure on Variation in Linkage Disequilibrium

Measurement of linkage disequilibrium involves two sampling processes. First, there is the sampling of gametes in the population to form successive generations, and this generates disequilibrium dependent on the effective population size (N_e) and the mating structure. Second, there is sampling of a finite number (n) of individuals to estimate the population disequilibrium.——Two-locus descent measures are used to describe the mating system and are transformed to disequilibrium moments at the final sampling. Approximate eigenvectors for the transition matrix of descent measures are used to obtain formulae for the variance of the observed disequilibria as a function of N_e, mating structure, n, and linkage or recombination parameter.——The variance of disequilibrium is the same for monoecious populations with or without random selfing and for dioecious populations with random pairing for each progeny. With monogamy, the variance is slightly higher, the proportional difference being greater for unlinked loci.     

Stimulation of gastrin secretion from the perfused rat stomach by somatostatin antiserum

The effect of a high capacity somatostatin antiserum on antral gastrin secretion was examined in an isolated vascularly perfused rat stomach preparation. Infusion of somatostatin antiserum diluted 1:1 and 1:9 with Krebs buffer solution produced significant increases in gastrin secretion throughout the period of infusion. Neither infusion of somatostatin antiserum diluted 1:99 nor infusion of control rabbit serum had any effect on gastrin secretion. The data indicate that antral somatostatin excercises a continous restraint on gastrin secretion in the basal state.     

The biological activity of catfish pancreatic somatostatin

Catfish pancreatic somatostatin, which contains eight additional amino acids on the amino terminus of a tetradecapeptide with considerable homology to tetradecapeptide somatostatin (SRIF), is a naturally occurring homology of the hypothalamic peptide. The purpose of these studies was to determibe the biological activity of this somatostatin homolog. Inhibition of ¹²⁵I-labelled tyr¹-SRIF binding to bovine pituitart plasma membranes by catfish pancreatic somatostatin was approximately 33% that of SRIF. Pancreatic somatostatin has full biological activity measured by inhibition of growth hormone release from isolated rat pituitary cells, but 0.01–0.1% the potency of SRIF. Pancreatic somatostatin at 100 ng/ml produced a 50–60% inhibition of insulin and glucagon secretion from perfused rat pancreas, while SRIF produced comparable inhibition at 10 ng/ml. This report demonstrates that a larger molecular form and natural homolog of SRIF, isolated from fish pancreas, has the same (but reduced) biological activities in rat assay systems as somatostatin originally isolated from sheep hypothalamus.