Simultaneous free and bound radioactive vitamin B12 urinary excretion test

The absorption of vitamin B(12) following the simultaneous administration of (58)Co B(12) and a complex of (57)Co B(12) with human gastric juice was assessed by measurement of urinary excretion of radioactivity. Sixteen control subjects, 13 patients with pernicious anaemia, and four who had had total gastrectomy were studied. The method proved a reliable means of detecting those with intrinsic factor deficiency.     

Relationship between lipofuscin granules and polyunsaturated fatty acids in the housefly, Musca domestica

The fractional volume occupied by lipofuscin granules in epithelial cells of the midgut or oenocytes of abdominal fat body of 3-day-old and 13-day-old male houseflies was determined in two groups of flies by electron microscopic morphometry. One group had developed from larvae reared on diets containing no added polyunsaturated fatty acids and the second from larvae reared on diets containing added linoleic acid. No polyunsaturated fatty acids could be detected in the lipids of the first group of flies using a method which would have detected their presence in amounts greater than 0.1% of the total esterified fatty acids. The second group contained at least two hundred times more than this minimal level. The volume of lipofuscin granules increased significantly (p less than 0.01) (about threefold for the fat body and twofold in midgut cells) between 3 days and 13 days of age but no statistically significant difference was seen between the two groups of flies at the same age. The results show that if lipofuscin formation depends on the oxidation of polyunsaturated fatty acids in the housefly, then extremely small amounts of the acids are involved which lie below the detection limit of the methods employed. The age-associated small increase of extractable fluorescence seen previously in the linoleic acid group of flies is not associated with an increase in the lipofuscin granules.     

Life expectancy in British Marfan syndrome populations

A total of 206 patients with Marfan syndrome were ascertained throughout genetic clinics in Wales and Scotland during the period 1970–1990. There were 45 deaths representing 22% of the cohort. Mean age at death was 45.3 ± 16.5 years. 50% median cumulative survival in the total cohort (n = 206) was 53 years for males and 72 years for females. Multivariate analysis confirmed severity as the best independent indicator of survival. These findings and survival curves will assist in the counselling of British families and individuals with Marfan syndrome.     

Role of nitric oxide in the biology, physiology and pathophysiology of reproduction

Following its benchmark discovery, nitric oxide (NO) is nowknown to play important functional roles in a variety of physiologicalsystems. Within the vasculature, NO induces vasodilation, inhibitsplatelet aggregation, prevents neutrophil/platelet adhesionto endothelial cells, inhibits smooth muscle cell proliferationand migration, regulates programmed cell death (apoptosis) andmaintains endothelial cell barrier function. NO generated byneurons acts as a neurotransmitter, whereas NO generated bymacrophages in response to invading microbes acts as an antimicrobialagent. Because neurons, blood vessels and cells of the immunesystem are integral parts of the reproductive organs, and inview of the important functional role that NO plays in thosesystems, it is likely that NO is an important regulator of thebiology and physiology of the reproductive system. Indeed, inthe past 10 years, NO has established itself as a polyvalentmolecule which plays a decisive role in regulating multiplefunctions within the female as well as the male reproductivesystem. This review provides an overview of the role of NO invarious reproductive organs under physiological and pathologicalconditions.     

Mycoplasma pulmonis Inhibits Electrogenic Ion Transport across Murine Tracheal Epithelial Cell Monolayers

Murine chronic respiratory disease is characterized by persistent colonization of tracheal and bronchial epithelial cell surfaces by Mycoplasma pulmonis, submucosal and intraluminal immune and inflammatory cells, and altered airway activity. To determine the direct effect of M. pulmonis upon transepithelial ion transport in the absence of immune and inflammatory cell responses, primary mouse tracheal epithelial cell monolayers (MTEs) were apically infected and assayed in Ussing chambers. M. pulmonis-infected MTEs, but not those infected with a nonmurine mycoplasma, demonstrated reductions in amiloride-sensitive Na⁺ absorption, cyclic AMP, and cholinergic-stimulated Cl⁻ secretion and transepithelial resistance. These effects were shown to require interaction of viable organisms with the apical surface of the monolayer and to be dependent upon organism number and duration of infection. Altered transport due to M. pulmonis was not merely a result of epithelial cell death as evidenced by the following: (i) active transport of Na⁺ and Cl⁻, albeit at reduced rates; (ii) normal cell morphology, including intact tight junctions, as demonstrated by electron microscopy; (iii) maintenance of a mean transepithelial resistance of 440 Ω/cm²; and (iv) lack of leakage of fluid from the basolateral to the apical surface of the monolayer. Alteration in epithelial ion transport in vitro is consistent with impaired pulmonary clearance and altered airway function in M. pulmonis-infected animals. Furthermore, the ability of M. pulmonis to alter transport without killing the host cell may explain its successful parasitism and long-term persistence in the host. Further study of the MTE-M. pulmonis model should elucidate the molecular mechanisms which mediate this reduction in transepithelial ion transport.Mycoplasmas, the smallest free-living prokaryotes, continue to be a significant cause of respiratory infections in a variety of animals, including humans (44). Their limited biosynthetic capability dictates that these organisms must both colonize and parasitize epithelial cell surfaces. It is therefore surprising that mycoplasmas produce diseases that are slowly progressing and chronic and yet often clinically inconspicuous. The molecular mechanisms responsible for this tenuous truce between the pathogen and the host cell have not yet been identified. Murine respiratory mycoplasmosis, a naturally occurring respiratory disease in laboratory rats and mice caused by Mycoplasma pulmonis (6, 8) and characterized by chronic, often lifelong tracheitis, bronchopneumonia, and bronchiectasis (7, 23, 28), would seem to be an ideal model with which to study these mechanisms. Although M. pulmonis-infected animals generate intense local and systemic immune responses (24, 33, 42, 43), they are incapable of eliminating the organism from the respiratory epithelium. Remodeling of the airways typically observed in infected animals, impairment of pulmonary clearance, and accumulation of mucus (23) suggest that M. pulmonis may compromise the ability of the epithelial cells to absorb and secrete fluid and electrolytes.Airway epithelial cells possess two major active transport processes, Na⁺ absorption and Cl⁻ section. Water, in turn, osmotically follows the transepithelial movement of these ions, thereby providing a fluid film between the mucus layer and the epithelial cell surface. The depth and composition of this fluid microenvironment must be carefully regulated to allow the exchange of gases and the humidification of the airway epithelium and to ensure proper mucociliary clearance (47, 49). The consequences of impaired fluid and electrolyte transport in the airways are strikingly apparent in cases of cystic fibrosis, a recessive genetic disease resulting from the loss of epithelial chloride channels (31, 48). The studies reported here were designed to determine whether M. pulmonis infection alters electrolyte transport across the murine tracheal epithelium.The effect of bacteria upon mammalian epithelia in the absence of immune and inflammatory cells can be systematically evaluated by using the Ussing chamber model. Short-circuit current (I_sc) studies have helped determine the mechanism by which cholera toxin (18) and other enterotoxins affect the intestinal mucosa (17, 35). Study of various types of epithelial cells by using the Ussing chamber model has also resulted in the identification of numerous microbial substances capable of directly altering the ion transport capacity of the airway epithelium (3, 20, 41).In the present study, control and M. pulmonis-infected mouse tracheal epithelial cells (MTEs) were evaluated in Ussing chambers. The results clearly show that M. pulmonis infection directly alters epithelial ion transport and that this alteration is species specific, dose and time related, and dependent upon the association of viable organisms with the apical cell surface.     

ATRX encodes a novel member of the SNF2 family of proteins: mutations point to a common mechanism underlying the ATR-X syndrome

It was shown recently that mutations of the ATRX gene give rise to a severe, X-linked form of syndromal mental retardation associated with alpha thalassaemia (ATR-X syndrome). In this study, we have characterised the full-length cDNA and predicted structure of the ATRX protein. Comparative analysis shows that it is an entirely new member of the SNF2 subgroup of a superfamily of proteins with similar ATPase and helicase domains. ATRX probably acts as a regulator of gene expression. Definition of its genomic structure enabled us to identify four novel splicing defects by screening 52 affected individuals. Correlation between these and previously identified mutations with variations in the ATR-X phenotype provides insights into the pathophysiology of this disease and the normal role of the ATRX protein in vivo.      

Calmodulin content in human prolactin-secreting pituitary adenoma: an inverse relationship to serum prolactin levels

Calmodulin content was evaluated in 3 prolactin-secreting pituitary adenomas (prolactinoma) and 3 normal anterior pituitary glands. The calmodulin content in the normal anterior pituitary tissue was quite consistent, 3.32 +/- 0.016 micrograms/mg protein. In contrast, calmodulin content varied almost 4-fold in the prolactinoma tissue (10.97, 8.50 and 3.00 micrograms/mg protein). Preoperative serum prolactin levels varied inversely with the prolactinoma calmodulin content (125, 257 and 3526 ng/ml, respectively). This study reveals that prolactinoma calmodulin content differs from normal, although it is not uniformly elevated as in other transformed tissues and that elevation of prolactinoma calmodulin content does not positively correlate with serum prolactin levels.     

Assessment of bioequivalence after subcutaneous and intramuscular administration of urinary gonadotrophins

The objective was to demonstrate bioequivalence between s.c. and i.m. administration of Humegon (FSH/LH ratio 1:1) and Normegon (FSH/LH ratio 3:1). In two randomized, single-centre, cross-over studies, 18 healthy volunteers on each formulation were assigned to one of the two administration sequences. Subjects were given single doses of one of the above gonadotrophins after endogenous gonadotrophin production had first been suppressed using high-dose oral contraceptive. Subsequently, rate (Cmax, tmax) and extent (AUC) of absorption of follicle stimulating hormone (FSH) and luteinizing hormone (LH) were determined for 14 days. For Cmax and AUC, analysis of variance (ANOVA) was performed on log-transformed data and for tmax ANOVA was performed on ranks. Intramuscular and s.c. injections of Humegon were bioequivalent with respect to the main pharmacokinetic parameters, being AUC and Cmax of FSH absorption. Intramuscular and s.c. injections of Normegon were bioequivalent with respect to the AUC of FSH and not bioequivalent with respect to the Cmax of FSH. For tmax of FSH as well as for most LH variables of both preparations, bioequivalence could not be proven due to the high intra- and interindividual variability and/or concentrations being close to the detection limit. Thus, the main pharmacokinetic FSH variables after i.m. and s.c. administration of Humegon and Normegon were bioequivalent.