Experimental diabetes in lactating sheep: effects of alloxan on plasma insulin, glucose, glucose kinetics and milk characteristics

After intravenous administration of alloxan (50 mg kg-1 liveweight) to lactating ewes, there were triphasic changes in plasma glucose and insulin. Almost immediately, plasma insulin decreased and hyperglycaemia occurred, then, between c. 5-12 h, insulin increased and ewes became hypoglycaemic. Thereafter, insulin decreased and glucose increased from c. 20 h after alloxan and the diabetic state was established. Changes in glucose production and utilization correlated with changes in plasma glucose. Exogenous insulin was administered from 30 h after alloxan, and it took some 2 weeks to stabilize ewes. During this period, when mild hyperglycaemia persisted, milk yields and feed intakes were decreased but milk fat content was elevated. Once ewes were stabilized, plasma glucose, milk yield, feed intake and milk fat content returned to levels prior to alloxan. These observations are consistent with insulin playing a role in the aetiology of the 'low milk fat syndrome' in the ruminant. It appears that the alloxan-treated, insulin-stabilized ewe would be a useful model for studying the role of insulin during lactation, but it is necessary to allow time for animals to overcome effects of administration of alloxan.     

Endophyte differentiation inCasuarina actinorhizae

Summary This is an ultrastructural study of development of infected cells in nitrogen fixing root nodules ofCasuarina spp. While several aspects of development are similar to those found in many other actinorhizae, unusual aspects of development of the host cell and differentiation of the endophyte inCasuarina are correlated with unusual changes in the wall of the infected cell. Instead of vesicles the endophyte forms atypical hyphae in mature infected cells. These unusual hyphal forms are termed intracellular hyphae. Intracellular hyphae are nonseptate hyphae which originate and terminate within the same host cell, and have a varying diameter and a multidirectional growth and branching pattern. A laminate surface layer previously undescribed on hyphae ofFrankia is a feature common to mostCasuarina endophytic hyphae and is probably similar chemically to the laminae comprising the multilamellate envelope of endophytic vesicles in other actinorhizae.This paper is Florida Agricultural Experiment Station Journal Series No. 7350.     

Screening for psychosocial problems among primary care patients: a pilot study.

The symptoms that a patient presents to the doctor are often not the underlying concern that prompted the consultation. The success of consultations involving a hidden diagnosis depends on how well the patient can express his or her concerns to the doctor and on how skilfully the doctor can encourage this. This study tested the feasibility and acceptability of having patients complete a brief health index questionnaire designed to help them describe their underlying concerns to the doctor. In two family medicine centres 996 patients were asked to complete a questionnaire while waiting to see the doctor; 724 (73%) did so. An evaluation of their responses showed the method to be acceptable to most. The doctors judged that it added valuable information in 41% of all consultations and in 73% of consultations in which the patient presented with psychologic complaints. There was, nevertheless, considerable variation among the physicians in their acceptance of the approach. This variability is discussed in the light of alternative models of how, in practical terms, to treat the psychosocial dimensions of a patient''s complaint.     

Separation of micro-organisms from meat and their rapid enumeration using a membrane filtration-epifluorescent microscopy technique

A new method of separating bacteria from beef mince has been developed, in which an alkaline protease, Alcalase 0.6 L, was used to degrade the meat proteins, leaving micro-organisms in suspension. The organisms were then counted, using a membrane filtration-epifluorescent microscopy technique. A correlation coefficient of 0.97 was obtained between this method and the standard plate count, indicating its suitability for use in quality control.     

Vitamin A deficiency and inflammation: the pivotal role of secretory cells in the development of atrophic, hyperplastic and metaplastic change in the tracheal epithelium in vivo.

We showed previously that the proliferation of hamster airway secretory cells decreases during vitamin A deficiency (VAD) but later increases when submucosal inflammation develops (Virchows Arch [B] 59:231-242, 1990). This observation has important biological implications since two morphological extremes (atrophy and quiescence versus hyperplasia and hyperproliferation) are reported in the literature for VAD tracheal epithelium in vivo. In the present study, histological slides of tracheal rings from 35-day-old control and VAD hamsters (Virchows Arch [B] 45:197-219, 1984) were reviewed again. Rings from VAD hamsters were selected based on the absence or presence of a florid submucosal inflammation. Quantitative analyses were made on the cartilaginous part of rings from the anterior third of the trachea. When inflammation was absent, a mucociliary pseudostratified epithelium was, for the most part, maintained. The mitotic rate (MR, 6 h colchicine blockade) of secretory cells was markedly reduced (29-fold) but that of basal cells was not changed significantly. Moreover, cell density was not changed by VAD but ciliated cells and secretory cells were decreased and basal cells were increased, proportionally. We call this "minimal morphological change." Thinning (atrophy) of the minimally changed epithelium was associated with focal cell sloughing. Small scattered foci of epidermoid metaplasia (multiple layers of highly keratinized cells which were extremely flat, so that the epithelium was thin and attenuated) were also seen. We call this "atrophic epidermoid metaplasia." When inflammation was present, hyperplastic changes (stratification and epidermoid metaplasia) predominated and cells were in mitosis at all epithelial levels (low, middle, superficial) except in the most superficial (terminally differentiated) squames. The tracheal epithelium was thickened and hypercellular. The cells were piled up at the stratified lesions, and epithelial height, cell density and epithelial MR were significantly increased compared with the non-inflamed VAD epithelium. The effects of VAD and inflammation on cell proliferation were analyzed further by studying 7 h bromodeoxyuridine (BrdU) labelling patterns of cells in VAD tracheal epithelium, with and without submucosal inflammation. In addition, inflammation was induced in "minimally changed epithelium" by mild mechanical injury. The BrdU labelling patterns confirmed that DNA synthesis by secretory cells is reduced markedly by VAD. However, this suppression is overidden by the influx of inflammatory cells (the nature of the stimulus is unknown). The results indicate that the morphological contrasts (atrophy and hyperplasia) seen in the trachea during VAD in vivo are related to extremes in proliferation rates of tracheal secretory cells, regulated by VAD alone (minimal replication) and by inflammation (maximal replication).     

Rhodopsin kinase: substrate specificity and factors that influence activity

Rhodopsin kinase was prepared from bovine retinas by the method of Sitaramayya [Sitaramayya, A. (1986) Biochemistry 25, 5460] with some minor modifications. The enzyme is able to phosphorylate bovine rhodopsin in the disk membrane, rhodopsin from other species, and rhodopsin solubilized in mild detergent (dodecyl maltoside). Rhodopsin kinase can phosphorylate synthetic peptides containing the appropriate sequences from bovine rhodopsin; however, the Km values for these peptides are about 3 orders of magnitude higher than that for rhodopsin or ATP. Some peptides from the cytosolic surface of rhodopsin inhibit the phosphorylation. These results suggest that more than one region of rhodopsin is involved in the interaction of rhodopsin of the kinase. Mg2+ is required for the Mg-ATP complex as shown by the observation that (ethylenedinitrilo)tetraacetic acid inhibits kinase activity. Second, free Mg2+ above the concentration required to complex all of the ATP present activates the kinase. Third, higher concentrations of Mg2+ yield Mg-ATP-Mg instead of Mg-ATP and therefore inhibit the kinase activity. Other physiologically important cations such as Ca2+, Na+, and K+ reduce the activity of the kinase, probably by forming a metal ion-ATP complex, thereby reducing the concentration of Mg-ATP. 5'-[p-(Fluorosulfonyl)benzoyl]adenosine (FSO2BzAdo), an inhibitor of kinases and ATPases, inhibits rhodopsin kinase according to pseudo-first-order kinetics. The relationship between the first-order constant and the concentration of FSO2BzAdo is hyperbolic. This indicates that a reversible complex between the ATP analogue and the enzyme is formed prior to the covalent attachment of the analogue to rhodopsin kinase.(ABSTRACT TRUNCATED AT 250 WORDS)     

Uridine sugar nucleotides modified in their nucleoside moieties and their effect on lipid-linked saccharide formationin vitro

Uridine diphospho glucose (UDP-Glc) and uridine diphospho N-acetylglucosamine (UDP-GlcNAc), modified in the uridine moiety by either periodate oxidation of the ribose ring or substitution at position 5 of the uracil ring with fluorine, have been tested as potential inhibitors of glucosyl monophosphoryl dolichol (Glc-P-Dol) or N,N-diacetylchitobiosyl pyrophosphoryl dolichol [GlcNAc)2-PP-Dol) assembly in chick embryo cell membranes. The periodate oxidised sugar nucleotides inhibited glycosyl transfer from their respective natural counterparts by 50% at 230 micron periodate oxidised UDP-Glc and 70 micron periodate oxidised UDP-GlcNAc respectively. Inhibition in both cases was irreversible and addition of exogenous Dol-P stimulated only the residual non-inhibited reaction. Periodate oxidised UDP-GlcNAc preferentially inhibited the transfer of GlcNAc to GlcNac-PP-Dol. The sugar nucleotide containing 5-fluorouridine were, on the other hand, alternative substrates for Glc-P-Dol or (GlcNAc)2-PP-Dol synthesis. FUDP-Glc was a good substrate for Glc-P-Dol formation; having Km and Vmax values equal to those of UDP-Glc, whereas FUDP-GlcNAc was a less efficient substrate for the formation of (GlcNAc)2-PP-Dol; having Km and Vmax values one half and one third respectively of those of UDP-GlcNAc.