Tranexamic acid loaded in a physically crosslinked trilaminate dressing for local hemorrhage control: Preparation, characterization, and in-vivo assessment using two different animal models

This work aimed at formulating a trilaminate dressing loaded with tranexamic acid. It consisted of a layer of 3 % sodium hyaluronate to initiate hemostasis. It was followed by a mixed porous layer of 5 % polyvinyl alcohol and 2 % kappa-carrageenan. This layer acted as a drug reservoir that controlled its release. The third layer was 5 % ethyl cellulose backing layer for unidirectional release of tranexamic acid towards the wound. The 3 layers were physically crosslinked by hydrogen bonding as confirmed by Infrared spectroscopy. Swelling and release studies were performed, and results proposed that increasing number of layers decreased swelling properties and sustained release of tranexamic acid for 8 h. In vitro blood coagulation study was performed using human blood and showed that the dressing significantly decreased coagulation time by 70.5 % compared to the negative control. In vivo hemostatic activity was evaluated using tail amputation model in Wistar rats. Statistical analysis showed the dressing could stop bleeding in a punctured artery of the rat tail faster than the negative control by 59 %. Cranial bone defect model in New Zealand rabbits was performed to check for bone hemostasis and showed significant decrease in the hemostatic time by 80 % compared to the control.

Cubosomal functionalized block copolymer platform for dual delivery of linagliptin and empagliflozin: Recent advances in synergistic strategies for maximizing control of high-risk type II diabetes

A well-made chitosan-PVP block copolymer platform was equipped with highly ordered and uniform nano-channels. This highly adhesive block copolymer platform was designed to ensure the efficient co-delivery of two synergistic-acting hypoglycemic drugs. Linagliptin oral bioavailability is 30% due to poor permeability and intestinal degradation. Its pharmacokinetics shows a non-linear profile. Empagliflozin exhibited decreased permeability and decreased solubility in aqueous media between pH 1 and 7.5. Cubosomes were functionalized as a good microdomain to guest and improve the physicochemical characteristics of drug molecules with decreased permeability and solubility. Cubosomes loaded with linagliptin (linagliptin cubosomes (LCs)) and empagliflozin (empagliflozin cubosomes ECs) were separately prepared using the top-down method and optimized by applying 23 factorial design. Optimized cubosomal systems LCs (F3) and ECs (F4) were incorporated into a chitosan-PVP gel to obtain dual cubosome-loaded platforms (LECF) optimized through 22 factorial design. The permeation study from the optimized LECF (C1) ensured enhanced empagliflozin permeation alongside continued efflux for linagliptin, resolving potential risks due to its non-linear plasma profile. The in-vivo study revealed that AUC(0-∞) of linagliptin and empagliflozin was enhanced by 2- and threefold, respectively. Therefore, the chitosan-PVP block copolymer platform buccal application for the co-delivery of linagliptin and empagliflozin could contribute to enhanced clinical effectiveness in treating diabetes.

The mitochondrial genome of Dendrobaena tellermanica Perel, 1966 (Annelida: Lumbricidae) and its phylogenetic position

Earthworms are an important ecological group that has a significant impact on soil fauna as well as plant communities. Despite their importance, genetic diversity and phylogeny of earthworms are still insufficiently studied. Most studies on earthworm genetic diversity are currently based on a few mitochondrial and nuclear genes. Mitochondrial genomes are becoming a promising target for phylogeny reconstruction in earthworms. However, most studies on earthworm mitochondrial genomes were made on West European and East Asian species, with much less sampling from other regions. In this study, we performed sequencing, assembly, and analysis of the mitochondrial genome of Dendrobaena tellermanica Perel, 1966 from the Northern Caucasus. This species was earlier included into D. schmidti (Michaelsen, 1907), a polytypic species with many subspecies. The genome was assembled as a single contig 15,298 bp long which contained a typical gene set: 13 protein-coding genes (three subunits of cytochrome c oxidase, seven subunits of NADH dehydrogenase, two subunits of ATP synthetase, and cytochrome b), 12S and 16S ribosomal RNA genes, and 22 tRNA genes. All genes were located on one DNA strand. The assembled part of the control region, located between the tRNA-Arg and tRNA-His genes, was 727 bp long. The control region contained multiple hairpins, as well as tandem repeats of the AACGCTT monomer. Phylogenetic analysis based on the complete mitochondrial genomes indicated that the genus Dendrobaena occupied the basal position within Lumbricidae. D. tellermanica was a rather distant relative of the cosmopolitan D. octaedra, suggesting high genetic diversity in this genus. D. schmidti turned out to be paraphyletic with respect to D. tellermanica. Since D. schmidti is known to contain very high genetic diversity, these results may indicate that it may be split into several species.

Hemostatic Alginate/Nano-Hydroxyapatite Composite Aerogel Loaded with Tranexamic Acid for the Potential Protection against Alveolar Osteitis

Wound control in patients on anticoagulants is challenging and often leads to poor hemostasis. They have a higher tendency to develop alveolar osteitis after tooth extraction. The application of a hemostatic dressing that has a high absorbing capacity and is loaded with an antifibrinolytic drug could help in controlling the bleeding. Alginate/nano-hydroxyapatite (SA/Nano-HA) composite aerogels loaded with tranexamic acid (TXA) were prepared. Nano-HA served as a reinforcing material for the alginate matrix and a source of calcium ions that helps in blood clotting. It influenced the porosity and the water uptake capacity. TXA release from SA/Nano-HA aerogels showed a biphasic profile for up to 4 h. Blood coagulation studies were performed on human whole blood. The TXA-loaded aerogel significantly reduced the clotting time by 69% compared to the control (p < 0.0001). Recalcification time was significantly reduced by 80% (p < 0.0001). Scanning electron microscopy analysis revealed the porous nature of the aerogels and the ability of the optimum aerogel to activate and adhere platelets to its porous surface. The cell migration assay showed that there was a delay in wound healing caused by the TXA aerogel compared to the control sample after treating human fibroblasts. Results suggest that the developed aerogel is a promising dressing that will help in hemostasis after tooth extraction.

264 Intertrochantic Hip Fracture Fixation at Musgrove Park Hospital

Background

Hip fractures, the commonest fragility fracture in the UK, carry a 6.7% 30-day mortality. NICE-CG124 guide advises extramedullary implants for trochanteric (AO3.1A1/2) and intramedullary nails for subtrochanteric fractures.

We carried out a retrospective study on the use of cephalomedullary nails (CMN) at MPH to determine compliance with CG124.

Method

National Hip Fracture Database (NHFD) from 2019 was reviewed. Trust records were used for fracture type, surgery, and reasons for deviation from CG124.

Results

201 fractures were identified. NHFD revealed 38 A3 fractures of which 36 underwent CMN, one SHS and one non-operative management. Of 163 A1/A2 fractures, 33 received CMN and 130 CHS.

Only 77% of the NHFD data was correct. Further analysis revealed 18 CMNs were used for AO1/2 injuries. All had justifiable reasons for deviation from CG124, although not documented.

Conclusions

There is scope to improve accuracy of NHFD data. Deviation from guidelines may be appropriate but reasons must be documented and, when appropriate, discussed with patient. Similar nationwide inaccuracy can have significant implications for research based upon NHFD data. To prevent input of incorrect data, our recommendations include: Consultant to confirm AO grade during trauma meetings Reason CMN used for AO1/2 fractures to be documented Monthly local NHFD data audit

The potential of intranasal delivery of nanocrystals in powder form on the improvement of zaleplon performance: in-vitro, in-vivo assessment

OBJECTIVE

The present work focuses on improving zaleplon (ZAP) performance through nanosizing its insoluble particles which were then delivered intranasally in powder form.

SIGNIFICANCE

Since nanopowders have an exceptional ability to cross cell membrane, their absorption is facilitated in the solid form. Hence, delivering insoluble ZAP nanocrystals (NC) through intranasal route improves its bioavailability due to both nanosization and the escape of hepatic metabolism.

METHODS

Nanocrystals were prepared by anti-solvent precipitation followed by probe sonication in presence of Soluplus^®, Poloxamer-188 (0.25%), sodium lauryl sulfate (0.5%), and mannitol. Physicochemical evaluation of the prepared NC was done by DSC and XRPD. TGA was performed for stability detection. Ex vivo permeation study through isolated cattle nasal mucosal membrane, in addition to an in vivo bioavailability study was performed for assessment of the prepared NC.

RESULTS

Nanosization to 200 nm contributed to the enhancement in dissolution ∼100% within 30 min and reduced half-life to 1.63 min. Confirmation of adsorption of polymers over NC' surface was elucidated. TGA confirmed their thermal stability. Ex vivo permeation study showed a 2.7 enhancement ratio in favor of the prepared NC. Both the extent and rate of NC absorption through nasal mucosa of rabbits were significantly higher (p ˂ .05) than in case of oral tablets. The relative bioavailability of NC was increased 3.14 times as compared to the Sleep aid^® tablets.

CONCLUSION

The intranasal delivery of nanoscale ZAP powder proved to be a successful alternative to oral formulations that suffer poor absorption and limited bioavailability.

A New Crystal Engineering Technique for Dissolution Enhancement of Poorly Soluble Drugs Combining Quasi-emulsion and Crystallo-co Agglomeration Methods

A target of best dissolution improvement of poorly soluble drugs is a necessity for the success of formulation in industry. The present work describes the preparation, optimization, and evaluation of a new spherical agglomeration technique for glimepiride as a model of poorly soluble drugs. It involved the emulsification of a drug solution containing a dispersed carrier that tailors the crystal habit of the drug to a perfect spherical geometry, in a poor solvent containing a hydrophilic polymer which imparts sphericity and strength to the formed agglomerates. The FTIR peaks of optimized product did not show any sign of chemical interaction between the drug and adsorbed carrier. The DSC and X ray diffractogram showed a peak characteristic of spherical agglomerates with much less intensity than that of glimepiride. The dissolution t_1/2 of the drug slightly decreased from 381 min to 334 min in plain agglomerates. Introducing polymers in the aqueous phase of emulsion led to an improvement in the dissolution, reflected in t_1/2 ranging from 118 to 231 min. Agglomerates prepared with Starlac/PVP demonstrated the most optimum physicochemical characteristics being spherical, with the best flowability and packability parameters. The t_1/2 was as short as 19 min. The new carrier/polymer system offered a synergistic combination that highly contributed in dissolution enhancement of glimepiride. The spheronization and amorphisation offered by the new technique could account for such improvement.

Comparison of Adiponectin Levels During the Menstrual Cycle Between Normal Weight and Overweight/Obese Young Females

To compare serum adiponectin changes across the menstrual cycle between normal weight and overweight/obese young women and its correlation with serum estradiol. Young women (n=56) with regular menstrual cycle had been grouped according to their BMI into normal weight group (n=26) and overweight /obese group (n=30). Blood samples were drawn during early follicular (FP), pre-ovulatory (OP) and luteal phases (LP) of menstrual cycle for serum adiponectin and estradiol levels determination using enzyme-linked immunosorbent assay. Adiponectin serum level showed a significant decreasing pattern across the phases of menstrual cycle in normal weight group. This pattern was absent in the overweight/obese group. In addition, serum adiponectin was lower in overweight/obese group compared to normal weight subjects through all phases of menstrual cycle. No correlation was found between adiponectin and estradiol levels in both groups. A significant variation of serum adiponectin level was detected across the menstrual cycle in females with normal weight. In comparison, overweight/obese group showed a relatively stable adiponectin level throughout the cycle. This lack of adiponectin variation might be added to the complex mechanisms lies behind obesity-related female infertility.

Association of anthropometric measurements with oxidant-antioxidant status among young Saudi females

Present study aimed to explore the levels and correlation of oxidative stress biomarkers with anthropometry in a population of young Saudi females. One hundred six normotensives, non-diabetic Saudi females, with minimally active lifestyle, based on their body mass index (BMI) were divided as; normal-weight (NW; n=52), overweight (OW; n=24) and obese (OB; n=30). Anthropometric measurements [BMI, Waist Circumference (WC), Waist-Hip Ratio (WHR), Body Density (BD), Body Adiposity Index (BAI), % Body fat] and oxidative stress biomarkers; Thiobarbituric acid reactive substances (TBARS), 8-hydroxy-2-deoxyguanosine (8-OH-2dG: indicative of DNA/RNA damage), Superoxide dismutase, Serum total antioxidant capacity) were recorded. There was statistically significant higher 8-OH-2dG (pg/ml) in OB compared to NW (800.63+/-6.19 vs. 780.22+/-3.34; p=0.007), as determined by one-way ANOVA and Tukey post hoc test. 8-OH-2dG was significantly and positively associated with BMI (r=0.286, p=0.004), WC (r=0.280, p=0.005), BAI (r=0.26, p=0.008), and % body fat (r=0.27, p=0.006). There may be significantly increased DNA damage in normoglycemic, normotensive obese adolescent females. This can be linked to the amount of adipose tissue in the body as depicted by strong positive association between DNA damage and BMI, WC, BAI, and % body fat.

The Impact of Amorphisation and Spheronization Techniques on the Improved in Vitro & in Vivo Performance of Glimepiride Tablets

Purpose: Triple solid dispersion adsorbates (TSDads) and spherical agglomerates (SA) present new techniques that extensively enhance dissolution of poorly soluble drugs. The aim of the present study is to hasten the onset of hypoglycemic effect of glimepiride through enhancing its rate of release from tablet formulation prepared from either technique.

Methods: Drug release from TSDads or SA tablets with different added excipients was explored. Scanning electron microscopy (SEM) and effect of compression on dissolution were illustrated. Pharmacodynamic evaluation was performed on optimized tablets.

Results: TSDads & SA tablets with Cross Povidone showed least disintegration times of 1.48 and 0.5 min. respectively. Kinetics of drug release recorded least half-lives (54.13 and 59.83min for both techniques respectively). Cross section in tablets displayed an organized interconnected matrix under SEM, accounting for the rapid access of dissolution media to the tablet core. Components of tablets filled into capsules showed a similar release profile to that of tablets after compression as indicated by similarity factor. The onset time of maximum reduction in blood glucose in male albino rabbits was hastened to 2h instead of 3h for commercial tablets.

Conclusion: After optimization of tablet excipients that interacted differently with respect to their effect on drug release, we could conclude that both amorphisation and spheronization were equally successful in promoting in vitro dissolution enhancement as well as providing a more rapid onset time for drug action in vivo.

T3 Regulates a Human Macrophage-Derived TSH-β Splice Variant: Implications for Human Bone Biology

TSH and thyroid hormones (T3 and T4) are intimately involved in bone biology. We have previously reported the presence of a murine TSH-β splice variant (TSH-βv) expressed specifically in bone marrow-derived macrophages and that exerted an osteoprotective effect by inducing osteoblastogenesis. To extend this observation and its relevance to human bone biology, we set out to identify and characterize a TSH-β variant in human macrophages. Real-time PCR analyses using human TSH-β-specific primers identified a 364-bp product in macrophages, bone marrow, and peripheral blood mononuclear cells that was sequence verified and was homologous to a human TSH-βv previously reported. We then examined TSH-βv regulation using the THP-1 human monocyte cell line matured into macrophages. After 4 days, 46.1% of the THP-1 cells expressed the macrophage markers CD-14 and macrophage colony-stimulating factor and exhibited typical morphological characteristics of macrophages. Real-time PCR analyses of these cells treated in a dose-dependent manner with T3 showed a 14-fold induction of human TSH-βv mRNA and variant protein. Furthermore, these human TSH-βv-positive cells, induced by T3 exposure, had categorized into both M1 and M2 macrophage phenotypes as evidenced by the expression of macrophage colony-stimulating factor for M1 and CCL-22 for M2. These data indicate that in hyperthyroidism, bone marrow resident macrophages have the potential to exert enhanced osteoprotective effects by oversecreting human TSH-βv, which may exert its local osteoprotective role via osteoblast and osteoclast TSH receptors.

Serum kisspeptin levels across different phases of the menstrual cycle and their correlation with serum oestradiol

OBJECTIVE

A rise in oestrogen in the preovulatory phase produces a GnRH-induced luteinising hormone surge. Oestrogen receptors are not found on GnRH neurons but these are present on kisspeptin neurons. That led us to hypothesise that serum kisspeptin levels may vary during various phases of the menstrual cycle in relation to serum oestradiol.

METHODS

Thirty female students, 18-25 years old, Saudi nationality, with a regular menstrual cycle, were recruited from various health colleges of the University of Dammam, Saudi Arabia. Three blood samples per volunteer were collected at three different times: the early follicular, preovulatory and luteal phase. Serum kisspeptin and oestradiol were measured using ELISA kits. Comparison between individual subjects during the various phases was done by one-way, repeated-measures ANOVA. To discover which specific means differed, Bonferroni post hoc test was applied. Pearsons correlation was used to find out the relationship.

RESULTS

There was a statistically significant increase (p < 0.001) in serum kisspeptin levels from the early follicular to the preovulatory phase (264.11±28.42 vs. 472.46±17.82 nmol/l respectively), and from the preovulatory to the luteal phase (472.46±17.82 vs. 724.79±36.85 nmol/l respectively). Oestradiol levels also increased significantly (p = 0.006) from the early follicular to the preovulatory phase (45.85±5.34 vs. 79.07±7.45 pg/ml respectively), Pearsons correlation revealed a statistically insignificant correlation between kisspeptin and oestradiol in all three phases.

CONCLUSION

Endogenous kisspeptin secretion seems to vary across the different phases of the menstrual cycle and is not related to serum oestradiol.

Effects of amlodipine administration and withdrawal on rat pituitary gonadotropins

OBJECTIVE

The study was aimed to observe the effect of amlodipine on rat pituitary gonadotropins after amlodipine administration and withdrawal.

METHODS

It was an experimental study done at Army Medical College, National University of Sciences and Technology, Islamabad, Pakistan from 2009-2010. Sixty adult male rats were divided into groups A and B. Each group was further subdivided into two subgroups of 15 rats each; A1 (control), A2 (control recovery), B1 (amlodipine-treated) and B2 (amlodipine recovery). Amlodipine, 0.04 mg/kg body weight daily for fifty days was given by means of gavage to groups B1 and B2. Groups A1 and A2 were given vehicle (0.5 ml distilled water). After 50 days, rats in groups A1 and B1 were sacrificed and their serum LH and FSH levels were measured by Enzyme Immunoassay method. Vehicle and amlodipine were withdrawn in groups A2 and B2, respectively, and the rats were left for recovery to take place for another fifty days. The above procedure was adopted for the measurement of LH and FSH levels in the recovered rats.

RESULTS

Amlodipine administration for 50 days resulted in a significant rise in serum LH (p < 0.01) whereas serum FSH remained unchanged (p ≥ 0.05). Serum LH in amlodipine-treated rats returned to normal after amlodipine withdrawal (p ≥ 0.05).

CONCLUSION

Amlodipine causes a reversible increase in serum LH but it has no effect on serum FSH (Fig. 2, Ref. 17).

Thyroid and bone: macrophage-derived TSH-β splice variant increases murine osteoblastogenesis

It is now firmly established that TSH may influence the physiology and patho-physiology of bone by activating osteoblasts and inhibiting osteoclast activity resulting in relative osteoprotection. Whether this influence is directly exerted by pituitary-derived TSH in vivo is less certain, because we have previously reported that the suppression of pituitary TSH does not remove such protection. Here, we have characterized the functional relevance of a novel form of the TSH-β subunit, designated TSH-βv, known to be produced by murine bone marrow cells. We found that fresh bone marrow-derived macrophages (MØs) preferentially produced TSH-βv and, when cocultured with CHO cells engineered to overexpress the full-length TSH receptor, were able to generate the production of intracellular cAMP; a phenomenon not seen in control CHO cells, such results confirmed the bioactivity of the TSH variant. Furthermore, cocultures of MØs and osteoblasts were shown to enhance osteoblastogenesis, and this phenomenon was markedly reduced by antibody to TSH-β, suggesting direct interaction between MØs and osteoblasts as observed under the electron microscope. These data suggest a new paradigm of local modulation of bone biology by a MØ-derived TSH-like molecule and raise the question of the relative contribution of local vs pituitary-derived TSH in osteoprotection.

Chocolate/cocoa and human health: a review

Chocolate/cocoa has been known for its good taste and proposed health effects for centuries. Earlier, chocolate used to be criticised for its fat content and its consumption was a sin rather than a remedy, associated with acne, caries, obesity, high blood pressure, coronary artery disease and diabetes. Therefore, many physicians tended to warn patients about the potential health hazards of consuming large amounts of chocolate. However, the recent discovery of biologically active phenolic compounds in cocoa has changed this perception and stimulated research on its effects in ageing, oxidative stress, blood pressure regulation, and atherosclerosis. Today, chocolate is lauded for its tremendous antioxidant potential. However, in many studies, contradictory results and concerns about methodological issues have made it hard for health professionals and the public to understand the available evidence on chocolate's effects on health. The purpose of this review is to interpret research done in the last decade on the benefits and risks of chocolate consumption.

Lipid rafts are triage centers for multimeric and monomeric thyrotropin receptor regulation

The TSH receptor (TSHR), a heptahelical G protein-coupled receptor on the surface of thyrocytes, is a major autoantigen and physiological regulator of the thyroid gland. Unlike other G protein-coupled receptors, the TSHR undergoes posttranslational cleavage of its ectodomain, leading to the existence of several forms of the receptor on the plasma membrane. We previously hypothesized that to achieve high fidelity and specificity of TSH ligand or TSHR autoantibody signaling, the TSHR may compartmentalize into microdomains within the plasma membrane. In support of this hypothesis we have shown previously that TSHRs reside in GM1 ganglioside-enriched lipid rafts in the plasma membrane of TSHR-expressing cells. In this study, we further explored the different forms of TSHRs that reside in lipid rafts. We studied both TSHR-transfected cells and rat thyrocytes, using both nondetergent biochemical analyses and receptor-lipid raft colocalization. Using the biochemical approach, we observed that monomeric receptors existed in both raft and nonraft fractions of the cell surface in the steady state. We also demonstrated that the multimeric forms of the receptor were preferentially partitioned into the lipid microdomains. Different TSHR forms, including multimers, were dynamically regulated both by receptor-specific and postreceptor-specific modulators. TSH ligand and TSHR antibody of the stimulating variety induced a decrease of multimeric forms in the raft fractions. In addition, multimeric and monomeric forms of the receptor were both associated with Gsalpha within and without the rafts. Although failure to achieve total lipid raft disruption prevented a conclusion regarding the relative power of TSHR signaling within and without the raft domains, these data showed clearly that not only were a significant proportion of TSHRs residing within lipid microdomains but that constitutive multimerization of TSHRs was actually regulated within the lipid rafts.

Monomerization as a prerequisite for intramolecular cleavage and shedding of the thyrotropin receptor

The TSH receptor (TSHR) undergoes intramolecular cleavage of the ectodomain yielding a two-subunit structure on the cell surface. Subsequently, the TSHR ectodomains (the alpha- or A-subunits) are shed from the cell surface. In this study we first confirmed TSHR alpha-subunit shedding from tagged-TSHR transfected Chinese hamster ovary cells. We found that TSH exacerbated this phenomenon of TSHR subunit shedding. The 125I-TSH cross-linking technique has been suggested as useful in the assessment of dynamic changes in TSHR processing. In our hands this technique did not detect any enhancement of cleavage by TSH. However, we found that the cross-linking method had an inherent insensitivity for studying receptor dynamics as exhibited by its inability to detect even major degrees of TSHR down-regulation. We, therefore, used a cell-based, double-antibody, flow cytometric immunoassay to quantitate TSHR cleavage in real time. We then found that different lines of Chinese hamster ovary TSHR cells, when treated with TSH, showed a time- and dose-dependent increase in TSHR cleavage in addition to ectodomain shedding. We previously reported that monoclonal TSHR stimulating antibody (MS-1) did not always act like TSH. In particular, MS-1 did not enhance TSHR cleavage. However, when we used the Fab fragment of MS-1, we were able to induce cleavage in a similar time frame to TSH. These results suggested that the intact bivalent antibody immobilized the TSHRs in their multimeric state and inhibited intramolecular cleavage. In support of these observations, fluorescence recovery after photo bleaching measurements demonstrated a greater increase in TSHR mobility with MS-1 Fab fragments than with the intact MS-1 IgG. In conclusion, these data indicated that monomer formation from multimeric TSHRs might be an important requirement for TSHR cleavage and TSHR ectodomain shedding.

Localization and regulation of thyrotropin receptors within lipid rafts

The TSH receptor (TSHR) is a prototypic G protein-coupled receptor with a large extracellular domain. We have previously demonstrated homophilic interactions of TSHRs and their existence as constitutive oligomers. However, we have also shown that TSH itself promotes the formation of receptor monomers. We hypothesized, therefore, that TSHR monomers induced by TSH ligand may move into lipid rafts before effective TSH-induced signaling by bringing the cognate signaling molecules resident in such rafts together with the TSHRs. Thus, we aimed to determine whether the TSHRs would partition into these lipid rafts. The B subunit of cholera toxin (CTxB) binds to lipid raft-enriched GM1 ganglioside and has been widely exploited to visualize lipid rafts. Using such a method, we demonstrated the presence of these GM1-enriched lipid microdomains in Chinese hamster ovary cells by using CTxB labeled with a red dye (Alexa 594). To provide evidence for the presence of TSHRs in lipid rafts, we stained Chinese hamster ovary cells expressing TSHRGFP with labeled CTxB. Our results demonstrated that the TSHRGFP complexes localized to GM1-enriched lipid raft microdomains as evidenced by colocalization of the green fluorescent protein tag with the labeled CTxB. Hence, we concluded that a significant proportion of TSHRs were constitutively associated with lipid rafts. Furthermore, upon activation of these stained raft-receptor complexes with increasing concentrations of TSH, we observed that the raft-receptor complexes decreased significantly. The relevance of such receptor movement out of the rafts suggested that these may be the receptors critical in the initiation of signal transduction

Functional assessment of the thyrotropin receptor-beta subunit

Posttranslational processing of the TSH receptor (TSHR) involves proteolysis of a single chain holoreceptor into TSHR-alpha (or A) and TSHR-beta (or B) subunits, which remain associated via disulfide bonds and which may then form oligomers. As both uncleaved and cleavage-derived forms of this receptor have been reported to bind TSH and transduce signals, reasons for this cleavage into alpha- and beta-subunits have remained enigmatic. Recently we suggested that TSHR cleavage was related to receptor oligomerization and now we have asked if cleavage influenced the binding of G proteins to this receptor. Furthermore, as TSHR-alpha subunits are subject to shedding from the cell surface membrane, we have examined whether the remaining TSHR-beta subunits could mediate signaling themselves, either constitutively and /or ligand-induced. We found that only the cleaved form of the TSHR in transfected Chinese hamster ovary cells was able to bind Gsalpha protein, suggesting that cleavage of the native TSH receptor was associated with receptor activation. We also found that independently expressed TSHR-beta subunits on stable cell lines were unable to mediate either constitutive or TSH-induced signaling, as monitored by their inability to induce cAMP accumulation. These data suggested that receptor cleavage was intimately associated with receptor activation in the wild-type TSH receptor and that the residual TSHR-beta subunits left on the thyroid cell membrane, after TSHR cleavage and subsequent TSHR-alpha shedding, were essentially silent and did not participate in signal transduction.

Oligomerization of the human thyrotropin receptor: fluorescent protein-tagged hTSHR reveals post-translational complexes

To examine thyrotropin (TSH) receptor homophilic interactions we fused the human TSH receptor (hTSHR) carboxyl terminus to green fluorescent protein (GFP) and the corresponding chimeric cDNA was expressed in Chinese hamster ovary cells. Fluorescent TSH receptors on the plasma membrane were functional as assessed by TSH-induced cAMP synthesis. The binding of TSH, as well as TSHR autoantibodies, induced time- and dose-dependent receptor capping. Fluorescence resonance energy transfer between receptors differentially tagged with GFP variants (RFP and YFP) provided evidence for the close proximity of individual receptor molecules. This was consistent with previous studies demonstrating the presence of TSHR dimers and oligomers in thyroid tissue. Co-immunoprecipitation of GFP-tagged and Myc-tagged receptor complexes was performed using doubly transfected cells with Myc antibody. Western blotting of the immunoprecipitated complex revealed the absence of noncleaved TSH holoreceptors. This further suggested that cleavage of the holoreceptor into its two-subunit structure, comprising disulfide-linked TSHR-alpha and TSHR-beta subunits, was required for the formation of TSHR dimers and higher order complexes.

Reversal of the CD4(+)/CD8(+) T-cell ratio in lymph node cells upon in vitro mitogenic stimulation by highly purified, water-soluble S3-S4 dimer of pertussis toxin

Pertussis toxin (PT), a holomer consisting of a catalytic S1 subunit and a B oligomer composed of S2-S4 and S3-S4 dimers, held together by the S5 subunit, exerts profound effects on immune cells, including T-cell mitogenicity. While the mitogenic activity of PT was shown to reside fully within the B oligomer, it could not be assigned to any particular B-oligomer component. In this study, we purified the S3-S4 dimer to homogeneity under conditions propitious to maintenance of the native conformation. In contrast to previous reports which suggested that both S3-S4 and S2-S4 dimers are necessary for mitogenic activity, our preparation of the highly purified S3-S4 dimer was as strongly mitogenic as the B oligomer, suggesting that the S3-S4 dimer accounts for the mitogenic activity of the B oligomer. Moreover, in vitro stimulation of naive lymphocytes by the S3-S4 dimer resulted in reversal of the normal CD4(+)/CD8(+) T-cell ratio from approximately 2:1 to 1:2. The reversal of the CD4(+)/CD8(+) T-cell ratio is unlikely to be due to preferential apoptosis-necrosis of CD4(+) T cells, as indicated by fluorescence-activated cell sorter analysis of annexin-stained T-cell subsets, or to preferential stimulation of CD8(+) T cells. The mechanism underlying the reversal requires further investigation. Nevertheless, the data presented indicate that the S3-S4 dimer may have potential use in the context of diseases amenable to immunological modulation.

Fluorescent probes: looking backward and looking forward

Probe technology has been advancing very rapidly but to study molecular events in real time, there has to be a discrete choice in the use of "probes" and the "labels" that they carry. In this minireview, we shed light on the use of fluorescent probes, especially the use of green fluorescent protein (GFP) and its variants as tools to cell biologists studying protein secretion and trafficking. The use of these GFP variants has further widened the application of Fluorescence Resonance Energy Transfer (FRET) in analyzing protein-protein interaction.

A dipstick immunobinding enzyme-linked immunosorbent assay for serodiagnosis of hepatitis B and delta virus infections

A simple, specific and economical dipstick immunobinding enzyme-linked immunosorbent assay (DIA) for detecting hepatitis B surface antigen (HBsAg) and antibodies to hepatitis delta virus (anti-HDV), utilizing cellulose nitrate membrane is described. Screening of 815 serum specimens for HBsAg by DIA and micro ELISA revealed a positivity of 22.69% and 22.94% respectively. In the detection of antibodies to delta antigen, DIA was compared with an indirect immunofluorescence technique using A3 cell line as antigen substrate and a commercial macro ELISA. Of the 143 HBsAg positive sera tested for anti-HDV, 59 (41.25%) were positive by both immunofluorescence and macro ELISA and 61 (42.65%) by DIA. While the positive and negative predictive values of DIA for HBsAg were 100% and 99.6%, for anti-HDV by DIA these were 96.7% and 100% respectively. Based on the simplicity of performance and the economical nature of the test system, DIA is recommended as a diagnostic tool for field surveys and small laboratories in developing countries.

Non-organ specific & organ-specific auto-antibodies in hepatitis-B virus associated glomerulonephropathies

Eighty eight patients of glomerulonephropathies (HBsAg positive 67; HBsAg negative 21) and 88 matched and healthy controls were screened for non-organ specific autoantibodies-ANA, AMA, ASMA and APCA by indirect immunofluorescent technique. The 2.3 per cent positivity in the test group and the 8 per cent positivity in the control group did not suggest the involvement of hepatitis-B virus (HBV), as an influencing or associated agent. When 48 patients with glomerulonephropathies and 23 controls were screened for liver cell membrane (LMA) and renal cell membrane antibodies (RMA) by indirect immunofluorescent technique using isolated rat hepatocytes and renal cells, 79.2 per cent LMA positivity was seen in the HBsAg positive group and 41.7 per cent in the negative group and RMA positivity was 58 per cent in the positive group and 25 per cent in the negative group. Simultaneous positivity for both LMA and RMA was recorded in 50 per cent of the HBsAg positive patients and 15.7 per cent of the negative ones. The results suggest the possibility of an organ specific autoimmune trigger more frequently in HBV associated glomerulonephropathy.

Comparison of a miniaturized culture test and sheep blood agar for the recovery of Group A streptococci from throat cultures

A miniaturized culture test (strep test) was compared with conventional sheep blood agar (SBA) for the detection of Group A streptococci (GAS) from throat swabs. A total of 355 throat cultures were obtained in duplicate from symptomatic children and assessed by the two methods after overnight incubation. GAS were detected in 109 specimens by the strep test, in 100 specimens by SBA and in 118 specimens by both methods. There was no significant difference between the recovery rate of GAS by the strep test (92.4%) and SBA (84.7%) (0.1 greater than P greater than 0.05). The strep test was 85.2% specific for detection of GAS. The rates of false positive and false negative reactions with the strep test were 24.3 and 4.3%, respectively. Beta-hemolytic streptococci other than Group A, Staphylococcus aureus and alpha-hemolytic streptococci produced false positive reactions. The viability of GAS on the strep test was also tested. GAS were recovered from 27 of 28 (96.4%) strep tests at 24 hours and 25 of 27 (92.6%) tests at 72 hours after inoculation. These results indicate that strep test is as sensitive as the conventional SBA method in recovering GAS. The strep test is simple to use, is easy to interpret and has a long shelf life. Because of the high rate of false positive results (24.3%), this test may not be the best alternative method to SBA for use in office practice.

Ceftriaxone diffusion into cerebrospinal fluid of children with meningitis

We evaluated the diffusion of ceftriaxone into the cerebrospinal fluid of 27 infants and children with meningitis who were receiving conventional antimicrobic therapy. Ceftriaxone was administered as a single 75 mg/kg dose and was given early or late or both in the course of the illness. Three hours after a dose, the mean cerebrospinal fluid ceftriaxone level was 5.7 micrograms/ml in patients studied early in the course of meningitis and 2.1 micrograms/ml in patients studied later in the illness. Six hours after a dose, the mean cerebrospinal fluid ceftriaxone levels early and late in meningitis were 7.2 and 2.5 micrograms/ml, respectively. The diffusion did not correlate with the leukocyte count or the protein or glucose content of the cerebrospinal fluid. Serial, simultaneous cerebrospinal fluid and plasma ceftriaxone levels were also determined in three additional patients with ventriculo-peritoneal shunt infections and external ventriculostomy drainage. The cerebrospinal fluid ceftriaxone levels in these patients ranged from 0.7 to 8.3 micrograms/ml. Our data indicate that ceftriaxone diffuses sufficiently and consistently into the cerebrospinal fluid to warrant its assessment in the treatment of meningitis.

Pharmacokinetic and clinical evaluation of moxalactam in infants and children

37 patients ranging in age from 9 months to 14 years, with various infections, were treated with moxalactam. The pharmacokinetics of the drug were studied in 18 patients. The mean plasma concentration 1 h after a 25 mg/kg intravenous dose was 41.4 micrograms/ml +/- 15.6 SD, the half-life was 1.5 h +/- 0.4 SD and the mean Vd was 550 ml/kg +/- 239 SD. The total body clearance of moxalactam was 4.1 ml/min/kg +/- 1.5 SD and the mean renal clearance 4.5 ml/min/kg +/- 2.8 SD. Between 52 and 107% of the administered dose was recovered in the urine within 8 h after administration. The pharmacokinetics after the first and multiple doses of moxalactam were similar, indicating no accumulation of the drug with repeated administration. The clinical response was adequate in 35 of 37 patients. Moxalactam was well tolerated and only minor and transient hematological abnormalities were observed.