Heterologous cell-cell interactions: thromboregulation, cerebroprotection and cardioprotection by CD39 (NTPDase-1)

Blood platelets maintain vascular integrity and promote primary and secondary hemostasis following interruption of vessel continuity. Biochemical or physical damage to the coronary, carotid or peripheral arteries is followed by excessive platelet activation and recruitment culminating in vascular occlusion and tissue ischemia. Currently inadequate therapeutic approaches to stroke and coronary artery disease are a public health issue. Following our demonstration of neutrophil leukotriene production from arachidonate released from activated aspirin-treated platelets, we studied interactions between platelets and other blood cells, leading to concepts of transcellular metabolism and thromboregulation. Thrombosis has a proinflammatory component whereby biologically active substances are synthesized by interactions between different cell types that could not individually synthesize the product(s). Endothelial cells control platelet reactivity via three biochemical systems-autacoids leading to production of prostacyclin and nitric oxide, and endothelial ecto-ADPase/CD39/NTPDase-1. The autacoids are fluid-phase reactants, not produced by tissues in the basal state. They are only synthesized intracellularly and released upon interactions of cells with an agonist. When released, autacoids exert fleeting actions in the immediate milieu, and are rapidly inactivated. CD39 is an integral component of the endothelial cell surface and is substrate-activated. It maintains vascular fluidity in the complete absence of prostacyclin and nitric oxide, indicating that they are ancillary components of hemostasis. Therapeutic implications for the autacoids have not been compelling because of their transient, local and fleeting action, and limited potency. Conversely, CD39, acting solely on the platelet releasate, is efficacious in three different animal models. It metabolically neutralizes a prothrombotic platelet releasate via deletion of ADP--the major recruiting agent responsible for formation of an occlusive thrombus. In addition, solCD39 reduced ATP- and ischemia-induced norepinephrine release in the heart. This reduction can prevent fatal arrhythmia. Moreover, solCD39 ameliorated the sequelae of stroke in CD39 null mice. CD39 represents the next generation of cardioprotective and cerebroprotective molecules.

Giant cell arteritis mimicking idiopathic orbital inflammatory disease

PURPOSE

To report an unusual presentation of giant cell arteritis, referred from primary care, mimicking orbital apex syndrome.

CASE REPORT

A 72 year old woman was referred with a two week history of pyrexia, dull right eye ache, 2mm of right proptosis, mild conjunctival chemosis and restriction of right eye movements.

RESULTS

An erythrocyte sedimentation rate (ESR) was 90 and fluorescein angiography showed almost complete choroidal non-perfusion suggestive of giant cell arteritis. Temporal artery biopsy confirmed the diagnosis.

CONCLUSIONS

Giant cell arteritis (GCA) typically presents with anterior ischemic optic neuropathy (AION), choroidal ischemia, central retinal artery occlusion, infrequently manifesting as an ocular motility problem, but has rarely been known to mimick idiopathic orbital inflammatory disease. Prompt recognition and therapy can minimize the chance of ipsilateral ocular involvement and protect the fellow eye.

In hydronephrosis less than 10 % kidney function is not an indication for nephrectomy in children

PURPOSE

To reduce the incidence of nephrectomy or hydronephrosis in children.

MATERIALS AND METHODS

From September 1998 to October 2000, we treated 58 patients with hydronephrosis; their ages ranged from 35 days to 11 years (mean age 4 years 7 months). All patients were subjected to a DTPA renogram with split function. In 12 patients (study group), kidney function was less than 10 % (range 0 - 10 %). Initially, nephrostomy was carried out in all 12 patients followed by Anderson-Hyne's pyeloplasty after 4 - 6 weeks. Postoperatively renal USG, urine r/m/e & c/s (routine and microscopic examination and culture and sensitivity test), blood urea, serum creatinine were assessed and DMSA scan and DTPA renogram with split functions were carried out in all patients.

RESULTS

In the study group, all 12 patients showed improvement of renal function (more than 10 %) after nephrostomy and in all of them pyeloplasty was subsequently carried out within 4 - 6 weeks. There were no significant pre-, peri- or postoperative complications.

CONCLUSIONS

Contrary to common practice we do not recommend nephrectomy for hydronephrotic kidneys which show < 10 % of renal function on renogram. The renal functional status improves significantly after a preliminary nephrostomy, thus avoiding the need for a straightforward nephrectomy in children along with all the possible long-term effects of a single kidney.

A randomised, prospective study comparing trabeculectomy augmented with antimetabolites with a viscocanalostomy technique for the management of open angle glaucoma uncontrolled by medical therapy

AIMS

To compare trabeculectomy with viscocanalostomy for the control of intraocular pressure (IOP) in open angle glaucoma (OAG) uncontrolled by medical therapy.

METHODS

48 patients (50 eyes) with uncontrolled OAG were randomised to either trabeculectomy (25 eyes) or a viscocanalostomy technique (25 eyes). Preoperatively, eyes were graded in terms of risk factors for drainage failure. Those undergoing trabeculectomy were given intraoperative antimetabolites (5-fluorouracil 25 mg/ml (5-FU), mitomycin C (MMC) 0.2 mg/ml and 0.4 mg/ml) according to a standard protocol. Antimetabolites were not used intraoperatively in eyes undergoing viscocanalostomy, but they were randomised to the use of viscoelastic (Healonid GV) for intraoperative intracanalicular injection.

RESULTS

There were no significant differences between the groups in age, sex, type of OAG, preoperative medications, risk factors for drainage failure, and preoperative IOP. Mean follow up was 19 months (range 6-24 months). It was 12 months or longer in all eyes, except one lost to follow up at 6 months. At 12 months, complete success (IOP <21 mm Hg without antiglaucoma medications) was seen in all eyes undergoing trabeculectomy (100%), but in only 64% of eyes undergoing viscocanalostomy (p<0.001). The mean IOP was lower at 12 months (p<0.001) with trabeculectomy and the number of eyes with IOPs of 15 mm Hg or less was greater (p<0.05). The mean IOP at 12 months was lower in eyes that had undergone viscocanalostomy using intraoperative intracanalicular Healonid GV injection compared to those where only balanced saline solution had been used (p<0.01). However, in terms of complete success there was no difference between the viscocanalostomy groups (p<0.1). With the exception of measurements at 1 week, visual recovery (logMAR acuity) was similar and laser flare and cell values showed little differences between the groups. Corneal topography and keratometry at 12 months were little different from preoperative values. Postoperative interventions (subconjunctival 5-FU and needling procedures) were similar between the groups. Transient complications such as early bleb leak and hyphaema were more common in the trabeculectomy group (p<0.05). Postoperative cataract formation was more common after trabeculectomy (p<0.05).

CONCLUSIONS

IOP control appears to be better with trabeculectomy. Viscocanalostomy is associated with fewer postoperative complications, although significant complications permanently impairing vision did not occur with either technique.

Crossreactivity of SLE autoantibodies with 70 kDa heat shock proteins of Mycobacterium tuberculosis

Heat shock proteins (hsp) may be involved in the initiation and perpetuation of autoimmune diseases. In order to investigate the possible role of hsp and other intracellular proteins of Mycobacterium tuberculosis in the autoantibody production in SLE, the immuno-crossreactivity of SLE autoantibodies with Mycobacterium tuberculosis sonic extract and hsp-70 kDa was investigated. These proteins showed significant binding with Protein A-Sepharose isolated SLE IgG. Western blotting of hsp-70 with SLE IgG showed strong recognition, suggesting possible involvement of hsp and other intracellular proteins of Mycobacterium tuberculosis in the autoantibody induction in SLE.

Salmonella meningitis: report of three cases in adults and literature review

Salmonella meningitis is an unusual complication of Salmonella sepsis and occurs almost exclusively in infants and young children. One case of Salmonella meningitis and two cases of cerebrospinal fluid (CSF) pleocytosis in adult patients with Salmonella bacteremia were studied and the literature was reviewed. On a retrospective review of the charts of 100 sequential patients with Salmonella typhi and S. paratyphi-positive blood cultures, we found one patient with fulminant Salmonella meningitis and two others with CSF pleocytosis. All three patients survived. The patient with Salmonella meningitis had significant residual neurologic sequela. Salmonella encephalopathy occurred in six other patients who presented with headache and were confused or drowsy. Cases of meningitis in adults do occur and are associated with a high morbidity and mortality. Newer cephalosporn antibiotics may be the therapy of choice in these infections.

Inhibition of platelet recruitment by endothelial cell CD39/ecto-ADPase: significance for occlusive vascular diseases

During their 7-9 day lifespan in the circulation platelets are mainly responsible for maintaining the integrity of the vasculature. In thrombocytopenic states, there is an increase in vascular permeability and fragility, presumably due to absence of this platelet function. In sharp contrast, biochemical or physical injury in the coronary, carotid or peripheral arteries induces platelet activation and platelet recruitment, which can culminate in thrombotic vascular occlusion. Since there is one death every 33 s from vascular occlusion in the United States, this situation constitutes a major public health issue. In the course of studying interactions between cells of the vascular wall and those in the circulation, we observed that platelets in close proximity to endothelial cells do not respond to agonists in vitro. Experiments initiated in the late 1980's cumulatively indicated that endothelial cell CD39--an ecto-ADPase--was mainly responsible for this phenomenon. CD39 rapidly and preferentially metabolizes ADP released from activated platelets. ADP is the final common pathway for platelet recruitment and thrombus formation, and platelet aggregation and recruitment are abolished by CD39. Our current hypothesis is that CD39 will be a novel antithrombotic agent for treating high risk patients who have activated platelets in their circulation--the identifying characteristic of coronary artery occlusion and thrombotic stroke. A recombinant, soluble form of human CD39 has been generated. This is solCD39, a glycosylated protein of 66 kDa whose enzymatic and biological properties are identical to the full-length form of the enzyme. In our in vitro experiments, solCD39 blocks ADP-induced human platelet aggregation, and inhibits collagen- and thrombin receptor agonist peptide-induced platelet reactivity. We studied solCD39 in vitro in a murine model of stroke, which was shown to be driven by excessive platelet recruitment. In studies with CD39 wild-type (CD39+/+) mice solCD39 completely abolished ADP-induced platelet aggregation, and strongly inhibited collagen- and arachidonate-induced platelet reactivity ex vivo. When solCD39 was administered prior to transient intraluminal middle cerebral artery occlusion, it reduced ipsilateral fibrin deposition, decreased (111)In-platelet deposition, and increased post-ischemic blood flow 2-fold at 24 hours. These results were superior to those we obtained with aspirin pre-treatment. CD39 null (CD39-/-) mice, which we generated by deletion of exons 4-6 (apyrase conserved regions 2-4), have a normal phenotype, normal hematologic profiles and bleeding times, but exhibit a decrease in post-ischemic perfusion and an increase in cerebral infarct volume when compared to genotypic CD39+/+ controls in our stroke model. "Reconstitution" of CD39 null mice with solCD39 reversed these pathologic changes. Thus, the CD39-/- mice were actually rescued from cerebral injury by solCD39, thereby fulfilling Koch's postulates. These experiments have led us to hypothesize that solCD39 has potential as a novel therapeutic agent for thrombotic stroke. In this review, we summarize our recent research results with CD39 and solCD39, and discuss our viewpoints on its present and future possibilities as a novel treatment for thrombosis.

Treatment of metastatic carcinoid tumours, phaeochromocytoma, paraganglioma and medullary carcinoma of the thyroid with (131)I-meta-iodobenzylguanidine [(131)I-mIBG]

OBJECTIVE

Meta-iodo-benzyl-guanidine labelled with 131-iodine [(131)I-mIBG] has been used extensively for imaging tumours originating from the neural crest but experience with its therapeutic use is limited, particularly for non-catecholamine secreting tumours. In order to assess the therapeutic response and potential adverse effects of the therapeutic administration of (131)I-mIBG, we have reviewed all patients who had received this form of treatment in our department.

DESIGN

Retrospective analysis of the case notes of patients with neuroendocrine tumours who received treatment with (131)I-mIBG and were followed-up according to a defined protocol in a given time frame.

PATIENTS

Thirty-seven patients (18 with metastatic carcinoid tumours, 8 metastatic phaeochromocytoma, 7 metastatic paraganglioma and 4 metastatic medullary carcinoma of the thyroid) treated with (131)I-mIBG over a 15-year period were included in this analysis.

MEASUREMENTS

The symptomatic, hormonal and tumoural responses before and after (131)I-mIBG therapy over a median follow-up duration of 32 months (range 5-180 months) were recorded. Of the 37 patients (22 males; median age 51 years, range 18-81 years), 15 were treated with (131)I-mIBG alone whereas the other 22 received additional therapy.

RESULTS

A total of 116 therapeutic (131)I-mIBG doses were administered [mean cumulative dose 592 mCi (21.9 GBq); range 200-1592 mCi (7.4-58.9 GBq)]. None of the patients showed a complete tumour response. However, 82% of patients treated with (131)I-mIBG alone and 84% who received additional therapy showed stable disease over the period of follow-up. Overall survival during the period of the study was 71%. The overall 5-year survival rate was 85% (95% confidence interval, 72-99%) for all patients and 78% (95% confidence interval, 55-100%) for the carcinoid group alone, according to Kaplan-Meier analysis. Symptomatic control was achieved in all the patients treated with (131)I-mIBG alone, and in 72% of those receiving additional therapy. Hormonal control was noted in 50% and 57% of patients, respectively. (131)I-mIBG therapy was safe and well tolerated. Serious side-effects necessitating the termination of (131)I-mIBG therapy were seen in only 2 of our patients.

CONCLUSIONS

(131)I-mIBG therapy produces symptomatic and hormonal improvement and moderate tumour regression/stabilization in patients with metastatic neuroendocrine tumours with minimal adverse effects. It may be a valuable alternative or additional therapeutic option to the currently available conventional treatment modalities.

Thromboregulation by endothelial cells: significance for occlusive vascular diseases

-During their 7- to 9-day lifespan in the circulation, platelets perform an ill-defined baseline function that maintains the integrity of the vasculature. In thrombocytopenic states, there is an increase in vascular permeability and fragility, which is presumably due to absence of this platelet function. In sharp contrast, biochemical or physical injury in the coronary, carotid, or peripheral arteries induces platelet activation and platelet recruitment, which can progress to thrombotic vascular occlusion. Because there is 1 death every 33 seconds from vascular occlusion in the United States, this problem has critical public health implications. In this review, we describe the characterization of a novel potential antithrombotic agent with a unique mode of action-biochemical "deletion" of ADP from an activated platelet releasate, which thereby inhibits platelet recruitment and further activation.

An increase in expression of a Mycobacterium tuberculosis mycolyl transferase gene (fbpB) occurs early after infection of human monocytes

Changes in the mRNA levels of two Mycobacterium tuberculosis genes (fbpB known as antigen 85B, and hspX known as Acr) were studied in infected human monocytes. Antigen 85B is an enzyme involved in cell wall biosynthesis and is also a major target of the immune response. Acr is a stress protein believed to be involved in the bacillary response to adverse conditions and in non-replicating persistence. During the first 24 h of intracellular infection, the intramonocyte 85B mRNA level increased 54-fold (P = 0.00001) and 14.6 times in comparison with the 16S ribosomal rRNA. In contrast, the Acr mRNA fell 14.3 times. Although monocyte cytokine production was very variable, the 24 h secretion of tumour necrosis factor (TNF)-alpha correlated with the 85B-16S RNA ratio at 24 h (r = 0.77, Pcorr < 0.01). Furthermore, the addition of exogenous TNF-alpha to cultures was associated with a twofold increase in the 85B-16S ratio and, conversely, neutralization of endogenous TNF-alpha reduced the ratio. As antigen 85B also induces TNF-alpha, the positive feedback implied by our findings suggests a previously unsuspected role for this protein in the immunopathogenesis of tuberculosis.

The current and potential contribution of asymbiotic nitrogen fixation to nitrogen requirements on farms: a review

Significant levels of biological nitrogen fixation from sources other than nodulated legumes have become a tantalizing prospect for decades. Since the benefit to agriculture of nitrogen fixation from nodulated legumes was established, there have been widespread efforts to promote the use of various asymbiotic diazotrophic bacteria to fix extra nitrogen in soil. Despite much optimism by scientists and farmers, this prospect remains to be realised. Recently, the prospect has been pursued with renewed enthusiasm and several commercialised products have appeared. What are the reasons for this fresh enthusiasm? Are the new products based on realistic assessments of their biological potential? Why has it taken so long to advance to a stage where there is still only limited evidence that verifies hope becoming reality? This review assesses the current contribution from asymbiotic nitrogen fixation and re-assesses the prospects for greater contributions from this source. Among the many aspects of this multi-faceted subject that will be considered are: (i) the range of free-living microbial strains currently contributing to signficant asymbiotic nitrogen fixation; (ii) the significance of nitrogen-fixing microbes naturally associated with plants; (iii) the significance of endophytic systems and their role in sugarcane and other Gramineae; (iv) the possibility of extending this range by introducing new strains or discovering new systems capable of contributing additional nitrogen fixation. The case will be made that conditions providing a sustainable contribution for more than a short time are usually missing in such systems so that spontaneous biological nitrogen fixation is usually transient. It will be argued further that if all the positive factors controlling spontaneity at the biothermodynamic level are exploited, significant biological nitrogen fixation may soon be achieved in some of these systems on farms.

Apoptosis and mitosis of parenchymal cells in the duct-ligated rat submandibular gland

Apoptosis and proliferation of parenchymal cells during atrophy of rat submandibular gland induced by double duct ligation were investigated using immunohistochemistry for proliferating cell nuclear antigen (PCNA), terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-digoxigenin nick end labelling (TUNEL) and transmission electron microscopy (TEM). At 2 and 3 days after ligation, increased PCNA positive cells and mitoses were seen in ducts; thereafter PCNA positive cells decreased in number. At 3 and 4 days, the acinar cell population rapidly decreased, with many remaining TUNEL positive acinar cells. During this period, TEM showed typical apoptotic acinar cells that were phagocytosed by adjacent acinar cells or intraepithelial macrophages. After 7 days, most acinar cells had disappeared, leaving prominent residual ducts; a few acinar cells remained, especially at the lobule periphery. Submandibular gland duct ligation thus induced marked depletion of acinar cell by apoptosis and a concurrent short-lived cycle of duct cell proliferation.

Twisted plywood structure of an alternating lamellar pattern in cellular cementum of human teeth

Human cellular cementum was examined by scanning electron microscopy to elucidate the manner of the alternate lamellar pattern forming the cellular cementum. Specimens were demineralized, trimmed with a freezing microtome, and treated by NaOH-maceration. This procedure was chosen to avoid artifacts in the fibril arrangement, and to study the fibrous architecture in detail. For comparison, non-demineralized, polished and HCl-etched specimens were also prepared. In the NaOH-macerated specimens, the lamellar pattern of the cellular cementum conformed to the twisted plywood principle of bone lamellation with a periodic rotation of matrix fibrils resulting in an alternating lamellar pattern. In contrast, matrix fibrils were irregularly arranged without indication of rotation of matrix fibrils in the polished and etched specimens. Our results suggest that polishing and etching procedures cause damage to fibrils and fibril arrangement.

Site-directed mutagenesis of human endothelial cell ecto-ADPase/soluble CD39: requirement of glutamate 174 and serine 218 for enzyme activity and inhibition of platelet recruitment

Endothelial cell CD39/ecto-ADPase plays a major role in vascular homeostasis. It rapidly metabolizes ADP released from stimulated platelets, thereby preventing further platelet activation and recruitment. We recently developed a recombinant, soluble form of human CD39, solCD39, with enzymatic and biological properties identical to CD39. To identify amino acids essential for enzymatic/biological activity, we performed site-directed mutagenesis within the four highly conserved apyrase regions of solCD39. Mutation of glutamate 174 to alanine (E174A) and serine 218 to alanine (S218A) resulted in complete and approximately 90% loss of solCD39 enzymatic activity, respectively. Furthermore, compared to wild-type, S57A exhibited a 2-fold increase in ADPase activity without change in ATPase activity, while the tyrosine 127 to alanine (Y127A) mutant lost 50-60% of both ADPase and ATPase activity. The ADPase activity of wild-type solCD39 and each mutant, except for R135A, was greater with calcium as the required divalent cation than with magnesium, but for ATPase activity generally no such preference was observed. Y127A demonstrated the highest calcium/magnesium ADPase activity ratio, 2.8-fold higher than that of wild-type, even though its enzyme activity was greatly reduced. SolCD39 mutants were further characterized by correlating enzymatic with biological activity in an in vitro platelet aggregation system. Each solCD39 mutant was similar to wild-type in reversing platelet aggregation, except for E174A and S218A. E174A, completely devoid of enzymatic activity, failed to inhibit platelet responsiveness, as anticipated. S218A, with 91% loss of ADPase activity, could still reverse platelet aggregation, albeit much less effectively than wild-type solCD39. Thus, glutamate 174 and serine 218 are essential for both the enzymatic and biological activity of solCD39.

Involvement of caspase-3 in epigallocatechin-3-gallate-mediated apoptosis of human chondrosarcoma cells

Green tea polyphenol-(-)epigallocatechin-3-gallate (EGCG)-is a potent chemopreventive agent in many test systems and has been shown to inhibit tumor promotion and induce apoptosis. In this study we describe a novel observation that EGCG displayed strong inhibitory effects on the proliferation and viability of HTB-94 human chondrosarcoma cells in a dose-dependent manner and induced apoptosis. Investigation of the mechanism of EGCG-induced apoptosis revealed that treatment with EGCG resulted in DNA fragmentation, induction of caspase-3/CPP32 activity, and cleavage of the death substrate poly(ADP-ribose)polymerase (PARP). Pretreatment of cells with a synthetic pan-caspase inhibitor (Z-VAD-FMK) and a caspase-3-specific inhibitor (DEVD-CHO) prevented EGCG-induced PARP cleavage. The induction of apoptosis by EGCG via activation of caspase-3/CPP32-like proteases may provide a mechanistic explanation for its antitumor effects.

The cytoskeletal effector xPAK1 is expressed during both ear and lateral line development in Xenopus

xPAK1, a probable effector of stress activated MAP-kinase SAPK1/JNK activation and cytoskeletal dynamics, was found to be ubiquitously expressed within the Xenopus laevis ear and lateral line system during the development and differentiation of these organs. xPAK1 expression was very strong in the otic placode from its condensation, and expression continued in the otic vesicle up until stage 35/36, after which it abruptly ceased. At stage 29/30 expression occurred specifically in the epithelium of the otic vesicle, which includes the prospective sensorial epithelium. Expression of xPAK1 was also observed in the lateral line system from stage 35/36, at which stage the lateral line primordia have begun to migrate from the region of the otic vesicle. Lateral line expression continued at least until stage 37/38, at which time xPAK1 was noted in association with the differentiating lateral line organs. To our knowledge, xPAK1 is the first ubiquitous lateral line marker that is also expressed in the ear. In the context of previous studies, our data suggest that xPAK1 either plays a role in the differentiation of the mechano-sensors of the auditory system or in the formation of the otic vesicle epithelium and the lateral line primordia.

Menstrual irregularity in women with acromegaly

Menstrual irregularity is common in women with acromegaly, occurring in 40-84%. Although it has been attributed to gonadotropin deficiency and/or PRL excess, it has not been evaluated in detail, and its pathogenesis is not well understood. To explore the various possible pathogenic mechanisms, we have analyzed the clinical, endocrinological, and radiological characteristics of 47 women with active acromegaly within the reproductive age range (15-41 yr) with respect to their menstrual pattern; 9 patients (19%) had normal cycles, 7 (15%) had oligomenorrhea, 29 (62%) had amenorrhea, and 2 (4%) had polymenorrhea. Compared to patients with normal cycles (n = 9), patients with menstrual irregularity (oligo/polymenorrhea or amenorrhea; n = 38) were more hirsute, had lower serum estradiol (normal: median, 76.5 pmol/L; range, 20-570; menstrual irregularity: median, 283; range, 140-431; P < 0.01), and sex hormone-binding globulin (SHBG; normal: median, 19.6 nmol/L; range, 5-52; menstrual irregularity: median, 48; range, 18-60; P < 0.01), but similar testosterone levels; in addition, patients with amenorrhea had higher serum GH (normal: median, 100 mU/L; range, 8.8-400; amenorrhea: median, 30; range, 10.7-120; P < 0.05). PRL levels in excess of 1000 mU/L were found in 16 of the 38 patients with menstrual irregularity compared to only 1 of the 9 patients with normal cycles. Patients with menstrual irregularity had a greater impairment of anterior pituitary function than patients with normal cycles. Acromegalic patients who were defined as estrogen sufficient (estradiol, >140 pmol/L) had clinical baseline endocrine profiles and LH responses to GnRH stimulation similar to those in patients with polycystic ovarian disease. There was a positive correlation between GH levels and tumor size (r = 0.35; P < 0.05) and an independent inverse correlation between GH and SHBG levels (r = -0.6; P < 0.01), which persisted even in patients who were estrogen sufficient, but there was no correlation between GH and estradiol levels; in addition, there was a negative correlation between estradiol levels and tumor size (r = -0.42; P < 0.05). Thirty-five of the patients with menstrual irregularity had meso- or macroadenomas and 3 had microadenoma, whereas 6 of the 9 patients with normal cycles had microadenomas. In conclusion, menstrual irregularity is common in women with acromegaly (81% of our patients). Amenorrheic patients have higher GH levels, are mainly estrogen deficient, and tend to have larger tumors than patients with normal cycles. However, the independent negative correlation between GH and SHBG levels suggests that GH may, directly or indirectly, lead to a fall in SHBG, possibly determined by the hyperinsulinemia known to occur in acromegaly. Low SHBG levels may contribute to the menstrual disturbance seen in acromegaly in addition to any gonadotropin deficiency or hyperprolactinemia and may account for hirsutism in the presence of normal testosterone levels.

The structure and function of the cemento-dentinal junction in human teeth

The structure and function of the cemento-dentinal junction were studied in human molars by light and electron microscopy. The cemento-dentinal junction was an approximately 1-3-micron-thick layer full of proteoglycans with mucopolysaccharides but containing fewer collagen fibrils than the root dentin and cementum. In places, cemental fibrils crossed the cemento-dentinal junction. These fibrils appeared to intermingle with dentinal fibrils. By enzymatic treatment of decalcified specimen with hyaluronidase and trypsin, the cemento-dentinal junction decreased or lost staining affinity to toluidine blue. Prolonged treatment caused the separation of cementum from the root dentin during routine histological processes. These data suggest that the adhesion of proteoglycans is more important than the intermingling of dentinal and cemental fibrils for the cemento-dentinal attachment.

HIV/AIDS in Bangladesh: an assessment of biomedical risk factors for transmission

Behavioural risk factors for HIV/AIDS in Bangladesh were reviewed in a preceding article in this journal. Omitted from that review was a discussion of potential biomedical risk factors including: (i) an unregulated blood supply system in which blood used in transfusions is not screened for HIV and is donated primarily by professional donors: (ii) unsterile injections in non-formal and formal health-care settings; and (iii) a high prevalence in high-risk groups of other sexually transmitted diseases (STDs) which may function as co-factors for HIV transmission, particularly if chronically untreated. Studies elsewhere in the world suggest that the unregulated blood supply system, in particular, poses a serious danger in terms of the spread of the HIV epidemic. While certain socio-cultural factors may be contributing to low levels of HIV in Bangladesh, the prevalence of biomedical and behavioural risk factors suggest the importance of implementing targeted cost-effective interventions now.

Antimicrobial susceptibilities and plasmid contents of Neisseria gonorrhoeae isolates from commercial sex workers in Dhaka, Bangladesh: emergence of high-level resistance to ciprofloxacin

Commercial sex workers (CSWs) serve as the most important reservoir of sexually transmitted diseases (STD), including gonorrhea. Periodic monitoring of the antimicrobial susceptibility profile of Neisseria gonorrhoeae in a high-risk population provides essential clues regarding the rapidly changing pattern of antimicrobial susceptibilities. A study concerning the prevalence of gonococcal infection among CSWs was conducted in Bangladesh. The isolates were examined with regards to their antimicrobial susceptibility to, and the MICs of, penicillin, tetracycline, ciprofloxacin, cefuroxime, ceftriaxone, and spectinomycin by disk diffusion and agar dilution methods. The total plasmid profile of the isolates was also analyzed. Of the 224 CSWs, 94 (42%) were culture positive for N. gonorrhoeae. There was a good correlation between the results of the disk diffusion and agar dilution methods. Some 66% of the isolates were resistant to penicillin, and 34% were moderately susceptible to penicillin. Among the resistant isolates, 23.4% were penicillinase-producing N. gonorrhoeae (PPNG). 60.6% of the isolates were resistant and 38.3% were moderately susceptible to tetracycline, 17.5% were tetracycline-resistant N. gonorrhoeae, 11.7% were resistant and 26.6% had reduced susceptibility to ciprofloxacin, 2.1% were resistant and 11.7% had reduced susceptibility to cefuroxime, and 1% were resistant to ceftriaxone. All PPNG isolates contained a 3.2-MDa African type of plasmid, and a 24.2-MDa conjugative plasmid was present in 34.1% of the isolates. Since quinolones such as ciprofloxacin are recommended as the first line of therapy for gonorrhea, the emergence of significant resistance to ciprofloxacin will limit the usefulness of this drug for treatment of gonorrhea in Bangladesh.