A minimally lipidated form of cell-derived apolipoprotein E exhibits isoform-specific stimulation of neurite outgrowth in the absence of exogenous lipids or lipoproteins

Within the central nervous system, apolipoprotein E (apoE) synthesis is increased in response to nerve injury, a finding that may reflect a role for apoE in neuronal remodeling. Recent studies show that apoE3 promotes and apoE4 inhibits neurite outgrowth in cultured neuronal cells. Interestingly, these isoform-specific effects are observed only when apoE is presented to cells in the presence of an exogenous lipid source such as rabbit beta-very low density lipoprotein (beta-VLDL), making it difficult to discern the biologically active form of apoE or to understand the role of the lipid source. In the present study we tested whether a cell-derived lipidated form of apoE can alter neurite outgrowth in the absence of beta-VLDL by constructing Neuro-2a cell lines expressing high levels of apoE. Our results showed that endogenous apoE3 stimulated neurite outgrowth, whereas the endogenous apoE4 isoform was neutral. Furthermore, beta-VLDL antagonized the stimulatory effects of the endogenous apoE3. Characterization of the secreted apoE3 indicated that the neurite outgrowth-stimulating activity could be recovered from culture medium with an anti-apoE immunoaffinity column and was present in a poorly lipidated particle with a density between 1.19 and 1.26 g/ml. These results indicated that the biological activity of apoE3 in stimulating neurite outgrowth was inherent in the cell-derived apoE particle and was not dependent on either (a) an interaction of apoE3 with an artificial lipid source or (b) independent actions of apoE3 and beta-VLDL.

Evaluation of a polymerase chain reaction-based universal heteroduplex generator assay for direct detection of rifampin susceptibility of Mycobacterium tuberculosis from sputum specimens

In a double-blind study, 655 sputum specimens were obtained from individuals suspected of having tuberculosis and were analyzed for the presence of Mycobacterium tuberculosis and rifampin susceptibility with use of a polymerase chain reaction (PCR)-based universal heteroduplex generator assay (PCR/UHG-Rif). Of the specimens containing viable M. tuberculosis, 100% of the smear-positive (n = 41) and 50% of the smear-negative (n = 6) specimens tested positive for the organism by PCR/UHG-Rif. Nineteen of 537 culture-negative specimens tested positive for M. tuberculosis by PCR/UHG-Rif and were from patients with confirmed tuberculosis who were receiving antituberculosis therapy at the time of specimen collection. Thirty-five specimens contained nontuberculous mycobacteria and were negative by PCR/UHG-Rif. Genotypic evidence of rifampin resistance in five of six culture-confirmed, rifampin-resistant isolates was obtained by PCR/UHG-Rif, yielding a sensitivity and specificity for the assay of 83% and 98.2%, respectively. These results demonstrate the feasibility of using a PCR-based assay directly on sputum specimens for simultaneous detection of M. tuberculosis and rifampin susceptibility, and they suggest that patients with smear-positive, untreated tuberculosis and those presenting with suspected drug-resistant tuberculosis are the most appropriate groups for testing by PCR/UHG-Rif.

A comparative approach to topical cyclosporine therapy

Topical cyclosporine has been used by veterinary ophthalmologists since 1989 for the treatment of ocular surface inflammatory disease and keratoconjunctivitis sicca (KCS). As well as ameliorating clinical signs of ocular surface lymphocyte-driven inflammation in the dog, cat and horse, topical cyclosporine significantly raises tear production in both normal and KCS-affected animals. A licensed ointment preparation of 0.2% cyclosporine, Optimmune (Schering-Plough), is now available for administration to dogs. In this paper we examine the mechanisms by which cyclosporine exerts both its immunomodulatory and its lacrimogenic actions. The pharmacokinetics of topical cyclosporine are examined to determine whether these effects are truly local or are influenced by generalised immunosuppression caused by systemic absorption of topically applied drug. The paper reviews the few side effects of cyclosporine preparations in the experience of veterinary ophthalmologists and the experimental evidence which appears to implicate the vehicle rather than the active agent cyclosporine as causing many of these effects. Given that topical cyclosporine has been so widely accepted as a valuable ophthalmic preparation in the veterinary world and licensed as such, it is surprising that human ophthalmologists have not employed the drug to the same extent for conditions from vernal keratoconjunctivitis to Sjögren's syndrome.

Lacrimal pseudotumour in a young bull terrier

An inflammatory mass arising from the lower lacrimal canaliculus of unknown cause is reported in a dog. A 10-month-old Staffordshire bull terrier was presented with a history of epiphora and a red mass protruding from the left lower lacrimal punctum. The tissue was removed and histopathological examination of the lesion revealed a mass of highly vascularised granulation tissue with areas of epithelial ulceration and multiple stromal haemorrhages. Fibrosis and collagen deposition were evident as was a cellular infiltrate composed primarily of neutrophils and plasma cells. Regrowth necessitated further attempts at complete excision before a permanent cure was achieved.

Scavenger receptor class B, type I (SR-BI) is the major route for the delivery of high density lipoprotein cholesterol to the steroidogenic pathway in cultured mouse adrenocortical cells

The class B, type I scavenger receptor, SR-BI, binds high density lipoprotein (HDL) and mediates the selective uptake of HDL cholesteryl ester (CE) by cultured transfected cells. The high levels of SR-BI expression in steroidogenic cells in vivo and its regulation by tropic hormones provides support for the hypothesis that SR-BI is a physiologically relevant HDL receptor that supplies substrate cholesterol for steroid hormone synthesis. This hypothesis was tested by determining the ability of antibody directed against murine (m) SR-BI to inhibit the selective uptake of HDL CE in Y1-BS1 adrenocortical cells. Anti-mSR-BI IgG inhibited HDL CE-selective uptake by 70% and cell association of HDL particles by 50% in a dose-dependent manner. The secretion of [3H]steroids derived from HDL containing [3H]CE was inhibited by 78% by anti-mSR-BI IgG. These results establish mSR-BI as the major route for the selective uptake of HDL CE and the delivery of HDL cholesterol to the steroidogenic pathway in cultured mouse adrenal cells.

Quality of life with an implanted left ventricular assist device

BACKGROUND

With the increasing use of left ventricular assist devices (LVADs) for longer-term support of patients awaiting cardiac transplantation, we must now consider whether to use these devices as alternatives to medical therapy when biologic hearts are needed but not forthcoming. This expansion of use depends as much on quality of life as it does on survival. To draw an inference about long-term quality of life with implanted LVADs, we studied "bridged" patients at our institution.

METHODS

We elicited, by standard gamble, the utilities (preferences) of bridged patients at three points in their care: before LVAD implantation, during LVAD support, and after cardiac transplantation.

RESULTS

Utility was 0.548 (+/-0.276) before implantation, 0.809 (+/-0.136) during LVAD support, and 0.964 (+/-0.089) after transplantation. For patients interviewed during all three states of health, the utilities were significantly different (p = 0.0009 by analysis of variance).

CONCLUSIONS

The quality of life with an LVAD was substantially better than with medical therapy, on par with renal transplantation (as established by others), and not as good as after cardiac transplantation. These results portend an acceptable quality of life for long-term use of LVADs for patients with end-stage heart failure and contribute to the growing body of evidence supporting a clinical trial to test this new use.

Role of polymerase chain reaction in the diagnosis of early leprosy

For 39 patients suspected of early leprosy, skin biopsies of the lesions were done and bisected. One piece was used for histopathologic examination and the other for polymerase chain reaction (PCR) studies to detect Mycobacterium leprae. The diagnosis of early leprosy was made clinically in 14 patients and by histopathologic study in 26 patients. Acid-fast bacilli were seen in the histopathologic sections of only two patients, and M. leprae were detected using PCR techniques in 11 patients. In one patient the diagnosis of leprosy was made only because of the detection of M. leprae in the PCR study. Since even in endemic countries the profile of leprosy is changing, detection of leprosy lesions in their early stages has become increasingly important. Since the finding of M. leprae is crucial in the confirmatory diagnosis of early leprosy, it is suggested that PCR studies to detect M. leprae be done wherever possible in conjunction with histopathologic examination. It is also recommended that the feasibility and the cost-effectiveness of both of these methods to find M. leprae be evaluated.

Evolving costs of long-term left ventricular assist device implantation

BACKGROUND

To examine the long-term costs of implanting a left ventricular assist device, we reviewed the initial hospitalization and outpatient costs for 12 patients who received a vented electric left ventricular assist device, and projected the first-year costs.

METHODS

We used the ratio-of-cost-to-charges method to measure hospital costs and payments for physician time. We examined time trends in the resource use of 50 pneumatic left ventricular assist device recipients, using actuarial techniques and regression modeling.

RESULTS

The average actual cost of left ventricular assist device support is $221,313 over an average of 9.5 months. If there had been no Food and Drug Administration regulatory policy precluding hospital discharge before 30 days, this value would have been $201,148. Based on this latter figure, the average predicted first-year cost is $219,139. The length of the intensive care unit stay, one of the most costly components of care, decreased significantly over time.

CONCLUSIONS

The high costs of left ventricular assist device implantation are similar to those reported for cardiac transplantation. Given their success in supporting survival, we anticipate that these devices will be similarly cost-effective. However, further research is imperative to determine the cost-effectiveness of these devices beyond the introductory phase, when costs, benefits, and Food and Drug Administration requirements have stabilized.

Renal protection by a dual ETA/ETB endothelin antagonist, L-754,142, after aortic cross-clamping in the dog

Renal insufficiency is a significant complication that occurs after surgical procedures, requiring cross-clamping of the aorta. The mechanism for this renal dysfunction is currently not known, but studies suggest a potential role of endothelin in mediating the insufficiency. Accordingly, the role of endothelin was assessed using the nonpeptidyl, dual ETA/ETB endothelin antagonist L-754,142 in a model of renal insufficiency in the anesthetized dog induced by cross-clamping the suprarenal aorta for 60 min, followed by 2 h of reperfusion. In vehicle-treated animals (saline, n = 8) after 2 h of reperfusion, plasma [ET-1] increased 66% and renal blood flow (RBF) was reduced by 38% compared with baseline. This decline was associated with an 84% increase in renal vascular resistance and a 54% reduction in GFR (baseline, 46 +/- 5 ml/min; 21 +/- 3 ml/min at 2 h; P < 0.01) and sodium reabsorption (baseline, 6.7 +/- 0.7 microEq/min; 3.0 +/- 0.5 microEq/min at 2 h, P < 0.01). After baseline measurements, pretreatment with L-754,142 at 0.3 mg/kg bolus + 0.1 mg/kg per h continuous infusion (low dose; n = 8) or 3.0 mg/kg bolus + 1 mg/kg per h infusion (high dose; n = 8) initiated 45 min before aortic cross-clamp led to a dose-dependent normalization of RBF and renal vascular resistance within 2 h of cross-clamp removal. GFR was also improved and returned to within 75% of baseline (P < 0.01 versus vehicle) by 2 h of reperfusion with L-754,142 (baseline, 55 +/- 5 ml/min; 42 +/- 5 ml/min at 2 h with the high dose). The improvement of GFR with L-754,142 treatment was associated with a preservation of sodium reabsorption compared with vehicle-treated animals. This study supports a role of endothelin in the pathogenesis of renal insufficiency after aortic cross-clamping and demonstrates that pretreatment with the dual ETA/ETB endothelin antagonist L-754,142 preserves RBF and sodium reabsorption, leading to a significant improvement in GFR.

Targeting nitric oxide (NO) delivery in vivo. Design of a liver-selective NO donor prodrug that blocks tumor necrosis factor-alpha-induced apoptosis and toxicity in the liver

We have designed a drug that protects the liver from apoptotic cell death by organ-selective pharmacological generation of the bioregulatory agent, nitric oxide (NO). The discovery strategy involved three steps: identifying a diazeniumdiolate ion (R2N[N(O)NO]-, where R2N = pyrrolidinyl) that spontaneously decomposes to NO with a very short half-life (3 s) at physiological pH; converting this ion to a series of potential prodrug derivatives by covalent attachment of protecting groups that we postulated might be rapidly removed by enzymes prevalent in the liver; and screening the prodrug candidates in vitro and in vivo to select a lead and to confirm the desired activity. Of five cell types examined, only cultured hepatocytes metabolized O2-vinyl 1-(pyrrolidin-1-yl)diazen-1-ium-1,2-diolate (V-PYRRO/NO) to NO, triggering cyclic guanosine 3',5'-monophosphate (cGMP) synthesis and protecting the hepatocytes from apoptotic cell death induced by treatment with tumor necrosis factor-alpha (TNF alpha) plus actinomycin D. In vivo, V-PYRRO/NO increased liver cGMP levels while minimally affecting systemic hemodynamics, protecting rats dosed with TNF alpha plus galactosamine from apoptosis and hepatotoxicity. The results illustrate the potential utility of diazeniumdiolates for targeting NO delivery in vivo and suggest a possible therapeutic strategy for hepatic disorders such as fulminant liver failure.

Perfusion during coronary and mitral valve surgery utilizing minimally invasive Port-Access technology

Minimally invasive surgery has been used in the treatment of some cardiovascular diseases. Port-Access surgery is a new minimally invasive technique that utilizes cardiopulmonary by-pass and a specialized catheter system that provides cardiopulmonary support and myocardial preservation. Extrathoracic cardiopulmonary support is established with femero-femoral bypass with kinetic assisted venous drainage. An endovascular catheter system allows for all the benefits of mechanical support as well as myocardial preservation. This catheter system includes an endoaortic balloon catheter which functions as an aortic cross clamp and antegrade cardioplegia delivery catheter, endopulmonary vent, and endocoronary sinus catheter used for administration of retrograde cardioplegia. An initial cohort of 20 patients was treated by the Port-Access surgical approach with cardiopulmonary bypass. Ten patients had coronary artery surgery and 10 patients had mitral valve surgery. The average bypass times were 94.4 min (coronary artery) and 152.8 min (mitral valve). The mean aortic occlusion times were 49.7 min (coronary artery) and 112.6 min (mitral valve). All patients were weaned from bypass. This initial patient series demonstrated that Port-Access surgery was feasible in selected patients.

PCR identification of Mycobacterium bovis BCG

The attenuated bacillus Calmette-Guérin (BCG) vaccine strain is derived from a virulent strain of Mycobacterium bovis. BCG is difficult to differentiate from other strains of M. bovis and other members of the M. tuberculosis complex by conventional methods. Recently, a genomic region designated RD1 was found to be present in all virulent M. bovis and M. tuberculosis strains tested but deleted from all BCG strains tested. With this information, a multiplex PCR method was developed to detect the RD1 deletion. A large collection of BCG and other M. tuberculosis complex strains from diverse host and geographic origins was tested. RD1 was deleted in 23 of 23 BCG strains. RD1 was present in 129 of 129 other M. tuberculosis complex strains. This multiplex PCR method can be used as a tool for the rapid and specific identification of BCG.

Effect of macrophage stimulation on collagen biosynthesis in the healing wound

Immunomodulators that enhance macrophage function have been shown to be beneficial in a number of wound-healing models in humans and in experimental animals. The exact mechanism of this improved healing is unclear. To assess the role of collagen biosynthesis, the immunomodulator glucan phosphate was utilized in two murine models of wound healing, i.e., colon anastomosis and full-thickness skin incision. Tensile strength was evaluated using computer-assisted constant velocity tensiometry. Collagen biosynthesis was determined by assaying hydroxyproline content of wound hydrolysates by N-(9-fluorenyl)methoxycarbonyl/o-phthalaldehyde high-performance liquid chromatography. Experimental animals were treated with (1-3)-beta-D-glucan phosphate (250 mg/kg) intravenously 24 hours prior to colon anastomosis or skin incision. A second dose of glucan phosphate was given immediately postoperatively. Control animals received dextrose and water (5% w/v) intravenously. Tensile strength and hydroxyproline content were measured on postoperative Day 3. In the skin wound model, glucan phosphate treatment increased (P < 0.05) tensile strength by 42 per cent (342.5 +/- 12.2 vs 241.8 +/- 4.8 g), and hydroxyproline content was increased by 23.5 per cent (242.0 +/- 14.4 vs 196.8 +/- 10.5 pmol/microg; P < 0.05). In the glucan phosphate group, colon tensile strength was significantly (P < 0.05) increased by 34 per cent (34.2 +/- 2.3 g vs 45.8 +/- 2.1 g), and hydroxyproline content was increased by 7 per cent (47.45 +/- 3.31 vs 44.34 +/- 3.74 pmol/microg). These data indicate that macrophage modulation with glucan phosphate will increase tensile strength in experimental colon and skin wounds. In addition, we observed a positive correlation between glucan phosphate treatment, wound tensile strength, and collagen biosynthesis.

Studies of canine leucocyte antigens: a significant advance in canine immunology

The Canine Leucocyte Antigen Workshop (CLAW) was set up to produce and circulate monoclonal antibodies directed against cell surface molecules defining specific leucocyte cell types in the dog. The antibodies produced by the workshop have been used in studies of the canine immune system. While many similarities between the dog and other animals have been demonstrated, workshop studies have identified some anomalies in this species: CD4 antigen for example is expressed not only on helper/inducer T-lymphocytes but also at high density on canine neutrophils. Workshop antibodies have been used to investigate lymphocyte populations in the normal dog and in a range of diseases from lymphocytic neoplasms through conditions with an immune-mediated component such as Leishmaniasis to potentially autoimmune disorders such as rheumatoid arthritis and chronic superficial keratitis.

Regulation by adrenocorticotropic hormone of the in vivo expression of scavenger receptor class B type I (SR-BI), a high density lipoprotein receptor, in steroidogenic cells of the murine adrenal gland

The class B, type I scavenger receptor, SR-BI, binds high density lipoprotein (HDL) and can mediate selective uptake of HDL cholesteryl esters by cultured cells. The high levels of expression of SR-BI in steroidogenic tissues and the importance of selective uptake from HDL as a source of cholesterol for steroidogenesis raised the possibility that SR-BI may participate in cholesterol delivery to steroidogenic tissues in vivo. We have used immunoblotting and immunohistochemical methods to show that SR-BI is specifically expressed in a distinctive pattern on the surfaces of steroid-producing cells in the murine adrenal gland's cortex and that its expression in vivo is induced by adrenocorticotropic hormone and suppressed by glucocorticoids. Thus, expression of SR-BI protein is coordinately regulated with adrenal steroidogenesis. These data provide strong support for the hypothesis that SR-BI is a physiologically relevant HDL receptor that provides substrate cholesterol for steroid hormone synthesis.

Carcinoma of the lung after heart transplantation

We have recently noted an unexpected high incidence of lung cancer in our population of cardiac allograft recipients. We conducted a retrospective review of cardiac transplantation at our institution to investigate the incidence, clinical course, and outcome of patients who developed lung cancer following heart transplantation. Nine patients--each with a history of smoking at 30 pack-years--developed lung cancer following heart transplantation, for an incidence of 1.56% of patients at risk. Eight of the patients were male > or = 50 years of age, representing 3.3% of the male transplant recipients in this age group. The interval from transplantation to diagnosis clustered around 3-5 years after transplantation, but in two instances (22%), a neoplasm was discovered within 6 months of transplantation. Almost half of the cancers were discovered incidentally, despite routine radiographic surveillance. Seven of 9 (78%) patients had stage IV disease at presentation. Median survival after diagnosis was 3 months, and five of the seven patients who died survived less than 4 months after diagnosis. We conclude that cardiac transplant recipients are at increased risk for development of lung cancer. Patients with a moderate to heavy smoking history might well be advised to undergo chest CT scanning in an aggressive search for occult lung cancer before cardiac transplantation is considered further. Finally, despite frequent radiologic examinations, these lung cancers are often diagnosed incidentally, are far advanced at the time of diagnosis, are not surgically resectable, and are poorly responsive to adjuvant therapy.

Outpatient left ventricular assist device support: a destination rather than a bridge

BACKGROUND

To evaluate the feasibility and efficacy of outpatient left ventricular assist devices as a bridge to transplantation, we reviewed the initial clinical experience with this modality at our institution.

METHODS

During January 1993 to November 1995, 12 male and 2 female patients with an average age of 47 +/- 17 years were supported for an average of 117 +/- 24 days with the Thermo Cardiosystems VE wearable left ventricular assist device. Seven patients were discharged home an average of 35 +/- 4 days after implantation.

RESULTS

No device failures occurred, although 29 controller malfunctions were identified during 1,640 total support days. All patients were able to safely maintain their devices. Outflow graft bleeding and driveline infection were responsible for two readmissions. No long-term anticoagulation treatment was used; one small thromboembolic episode occurred, but without significant long-term sequelae.

CONCLUSIONS

None of the 7 patients released from the hospital died, and all were able to successfully maintain their devices at home. Hospital discharge of patients supported with left ventricular assist devices has allowed long-term evaluation of this technology, and the findings should prompt study of their use as a long-term alternative treatment to medical management for congestive heart failure.

Generation of nitric oxide from S-nitrosothiols using protein-bound Cu2+ sources

BACKGROUND

We have recently shown that S-nitrosothiols (RSNOs) decompose in aqueous buffer to give nitric oxide, an important signalling molecule, and the corresponding disulphides. This occurs by reaction with Cu+ generated from Cu2+ (supplied as hydrated Cu2+) by thiolate reduction. To establish whether these reactions are feasible in vivo, we set out to determine whether Cu2+ bound to an amino acid, a tripeptide or to human serum albumin (HSA) could serve as a Cu+ source for generation of NO from S-nitrosothiols.

RESULTS

Experiments with Cu2+ bound to the tripeptide Gly-Gly-His or to two histidine molecules or to HSA showed that Cu+ was released (and trapped with neocuproine) when the copper source was treated with a thiol at pH 7.4. RSNO decomposition was achieved with all three copper sources, although not as rapidly as with added hydrated Cu2+. Decomposition was also catalyzed by ceruloplasmin.

CONCLUSIONS

These results show clearly that amino-acid- and protein-bound Cu2+ can be reduced by thiolate ion to Cu+, which will generate NO from RSNO species, thus providing a realistic model for these reactions in vivo.

Apolipoprotein A-I is required for cholesteryl ester accumulation in steroidogenic cells and for normal adrenal steroid production

In addition to its ability to remove cholesterol from cells, HDL also delivers cholesterol to cells through a poorly defined process in which cholesteryl esters are selectively transferred from HDL particles into the cell without the uptake and degradation of the lipoprotein particle. The HDL-cholesteryl ester selective uptake pathway is known to occur in human, rabbit, and rodent hepatocytes where it may contribute to the clearance of plasma cholesteryl ester. The selective uptake pathway has been studied most extensively in steroidogenic cells of rodents in which it accounts for 90% or more of the cholesterol destined for steroid production or cholesteryl ester accumulation. In this study we have used apo A-I-, apo A-II-, and apo E-deficient mice created by gene targeting in embryonic stem cells to test the importance of the three major HDL proteins in determining cholesteryl ester accumulation in steroidogenic cells of the adrenal gland, ovary, and testis. apo E and apo A-II deficiencies were found to have only modest effects on cholesteryl ester accumulation. In contrast, apo A-I deficiency caused an almost complete failure to accumulate cholesteryl ester in steroidogenic cells. These results suggest that apo A-I is essential for the selective uptake of HDL-cholesteryl esters. The lack of apo A-I has a major impact on adrenal gland physiology causing diminished basal corticosteroid production, a blunted steroidogenic response to stress, and increased expression of compensatory pathways to provide cholesterol substrate for steroid production.

Receptor binding and internalization of a water-soluble (1--&gt;3)-beta-D-glucan biologic response modifier in two monocyte/macrophage cell lines

Glucan phosphate, a water-soluble, chemically defined (1--&gt;3)-beta-D-glucan biologic response modifier, has been reported to exert antisepsis activity and accelerate wound healing. In this study we describe the specific binding of glucan phosphate to human and murine monocyte/macrophage cell lines, U937 and J774A.1, respectively. At 37 degrees C, equilibrium binding was rapidly achieved, i.e., within 1 min. In U937 cells, binding occurred with an affinity (Kd) of 37 microM and a Bmax of 65 x 106 binding sites/cell at 37 degrees C. In J774A.1 cells, glucan phosphate bound with an affinity (Kd) of 24 microM and a Bmax of 53 x 106 binding sites/cell at 37 degrees C. In both cases there was insignificant nonspecific binding. We further demonstrated that bound glucan phosphate cannot be displaced by a 50-fold excess of unlabeled ligand, suggesting internalization of glucan phosphate. Transmission electron microscopy showed significantly increased cytoplasmic vacuolization and significantly decreased mitotic activity in glucan phosphate-treated U937 cells compared with that in untreated cells. Pullulan, a random coil alpha-(1--&gt;4)-(1--&gt;6)-linked glucose polymer that served as a control, did not compete for the same binding site as glucan phosphate in either cell line, indicating the specificity of the binding site for (1--&gt;3)-beta-D-glucans. We conclude that water-soluble pharmaceutical grade (1--&gt;3)-beta-D-glucan phosphate specifically binds to and is internalized by U937 and J774A.1 cells.

Receptor binding and internalization of a water-soluble (1-->3)-beta-D-glucan biologic response modifier in two monocyte/macrophage cell lines

Glucan phosphate, a water-soluble, chemically defined (1-->3)-beta-D-glucan biologic response modifier, has been reported to exert antisepsis activity and accelerate wound healing. In this study we describe the specific binding of glucan phosphate to human and murine monocyte/macrophage cell lines, U937 and J774A.1, respectively. At 37 degrees C, equilibrium binding was rapidly achieved, i.e., within 1 min. In U937 cells, binding occurred with an affinity (Kd) of 37 microM and a Bmax of 65 x 106 binding sites/cell at 37 degrees C. In J774A.1 cells, glucan phosphate bound with an affinity (Kd) of 24 microM and a Bmax of 53 x 106 binding sites/cell at 37 degrees C. In both cases there was insignificant nonspecific binding. We further demonstrated that bound glucan phosphate cannot be displaced by a 50-fold excess of unlabeled ligand, suggesting internalization of glucan phosphate. Transmission electron microscopy showed significantly increased cytoplasmic vacuolization and significantly decreased mitotic activity in glucan phosphate-treated U937 cells compared with that in untreated cells. Pullulan, a random coil alpha-(1-->4)-(1-->6)-linked glucose polymer that served as a control, did not compete for the same binding site as glucan phosphate in either cell line, indicating the specificity of the binding site for (1-->3)-beta-D-glucans. We conclude that water-soluble pharmaceutical grade (1-->3)-beta-D-glucan phosphate specifically binds to and is internalized by U937 and J774A.1 cells.

Current concepts in the management of canine cataract: a survey of techniques used by surgeons in Britain, Europe and the USA and a review of recent literature

One of the authors (D. L. W.) visited ophthalmologists in Great Britain, Europe and the USA to assess current practice in the surgery of cataracts in dogs. This paper describes the results of these visits and provides a survey of the literature. The success rates in canine cataract surgery have increased markedly in the last 10 years, particularly as a result of the introduction of phacoemulsification techniques and the reduction in the use of extracapsular cataract extraction; these new techniques and the problems they seek to overcome are discussed. The paper also considers the developing field of intraocular lens implantation, the rationale behind such developments and the benefits and potential problems which may occur after the extraction of a cataract and the implantation of a lens.

Characterization of rpsL and rrs mutations in streptomycin-resistant Mycobacterium tuberculosis isolates from diverse geographic localities

Two genes (rpsL and rrs) with mutations associated with streptomycin resistance in Mycobacterium tuberculosis were characterized in 78 streptomycin-resistant and 61 streptomycin-susceptible isolates recovered from patients living in the United States, South America, Europe, Africa, and Asia. Fifty-four percent of the 78 resistant organisms had missense mutations in codon 43 of rpsL resulting in a K-43-->R substitution. Mutations in codon 88 of rpsL were also identified in four Asian isolates.

Pharmacology of L-744,453, a novel nonpeptidyl endothelin antagonist

L-744,453 ((+/-)3-[4-(1-carboxy-1-(3,4-methylenedioxyphenyl)methoxy)-3,5-diprop ylphenyl methyl]-3H-imidazo[4,5-c]pyridine) is an endothelin (ET) receptor antagonist from a new structural class, the dipropyl-alpha-phenoxyphenylacetic acid derivatives. L-744,453 competitively and reversibly inhibits [125I]-ET-1 binding to Chinese Hamster Ovary cells expressing cloned human ET receptors (K(i)s: hET(A)=4.3 nM; hET(B)=232 nM), and is selective for endothelin receptors compared to other peptide receptors. It is an antagonist of ET-1 stimulated phosphatidyl inositol hydrolysis in rat uterine slices (IC50=220 nM) and exhibits no agonist activity. This compound also inhibits ET-1 stimulated contraction of rat aortic rings with a K(b) value of 50 nM. L-744,453 protects against ET-1 induced lethality in mice after i.v. (AD50=13 mg/kg i.v.) or oral administration. This compound also antagonizes ET-1 induced increases in diastolic blood pressure in conscious normotensive rats (AD50=0.67 mg/kg i.v.) and anesthetized ferrets (AD50=1.6 mg/kg i.v.). L-744,453 is a potent, selective, orally active endothelin antagonist which may be useful in elucidating the role of endothelin in normal and pathophysiological states.

Estrogen induces the assembly of a multiprotein messenger ribonucleoprotein complex on the 3'-untranslated region of chicken apolipoprotein II mRNA

UV cross-linking was used to identify estrogen-induced hepatocyte proteins that bind to apoII mRNA. Probes spanning the entire message revealed the presence of eight estrogen-induced proteins cross-linked to the 3'-untranslated region (UTR), but not to the coding region or the 5'-UTR. Two estrogen-induced proteins of 132 and 50 kDa were either absent or barely detectable in control animals, whereas six additional proteins of 93, 83, 74, 65, 58, and 45 kDa were clearly present in control animals and increased 2-5-fold by estrogen. A similar profile of estrogen-induced proteins was seen with the 3'-UTRs of the estrogen-regulated mRNAs for apoB and vitellogenin II, but not with the 3'-UTRs of the non-estrogen-regulated mRNAs for apoA-I and glyceraldehyde-phosphate dehydrogenase. These findings indicate that the estrogen-induced proteins discriminate among mRNAs and suggest that they interact selectively with the family of estrogen-regulated mRNAs. The estrogen-induced proteins are found in the cytoplasmic fraction of liver extracts, and a subset of them are also found in adrenal glands, testes, heart, brain, and kidneys, but they are estrogen-induced only in the liver. Deletion analysis defined a 150-nucleotide region of the apoII 3'-UTR that is necessary for maximal binding of the estrogen-induced proteins. An internal deletion of endonucleolytic cleavage sites previously identified within the apoII 3'-UTR selectively reduced the binding of the 58-kDa protein. These findings reveal remarkable complexity in estrogen-stimulated protein-RNA interactions within the 3'-UTRs of estrogen-regulated mRNAs. These proteins may participate in the mRNA degradation process or in other aspects of cytoplasmic mRNA metabolism that accompany estrogen-stimulated vitellogenesis.

Characterization of the catalase-peroxidase gene (katG) and inhA locus in isoniazid-resistant and -susceptible strains of Mycobacterium tuberculosis by automated DNA sequencing: restricted array of mutations associated with drug resistance

The catalase-peroxidase gene (katG) and a two-gene locus (inhA) containing mutations associated with resistance to isoniazid in Mycobacterium tuberculosis were sequenced in 34 resistant and 12 susceptible strains. Virtually all resistant organisms had amino acid changes in KatG or nucleotide substitutions upstream of inhA. A region of katG encoding two amino acids frequently altered in resistant strains (residues Ser315 and Arg463) and the inhA locus were sequenced in 10 susceptible and 51 isoniazid-resistant isolates from the Netherlands. Most (84%) of the resistant isolates had mutations in katG or the inhA locus or lacked katG. Together, approximately 75% of isoniazid-resistant isolates had replacements at amino acids 315 or 463 in KatG or nucleotide substitutions upstream of inhA. All 16 strains of Mycobacterium bovis and Mycobacterium microti studied had Leu463 rather than Arg463 in KatG, an observation consistent with the hypothesis that Leu463 is the ancestral condition in M. tuberculosis.

Psychosocial evaluation and prediction of compliance problems and morbidity after heart transplantation

We examined prospectively determined psychosocial evaluation data in 125 consecutive adult patients undergoing heart transplantation from January 1992 to April 1994 to determine their associations with morbidity, mortality, and compliance. Prospective ratings included age, sex, weight, education, social support, living arrangements, motivation, knowledge and expectations about transplantation, intercurrent social stressors, substance abuse, personality disorder, cognitive impairment, other psychiatric disorders, and the evaluating psychiatrist's global assessment of psychosocial risk. Additional variables evaluated were support group attendance and waiting list time. We examined outcomes including patient survival, compliance, episodes of rejection and infection, development of transplant coronary artery disease, number of missed appointments, and maintenance of ideal body weight. The posttransplant follow-up period was 13.8 +/- 9.9 months (mean +/- SD). In univariate analyses, compliance problems were associated with substance abuse history (P = .0007), personality disorder (P = .007), living arrangements (P = .02), and global psychosocial risk (P = .001). The number of rejection episodes was associated with global psychosocial risk (P = .029), and transplant coronary artery disease was inversely associated with education (P = .01). Survival was not associated with any of the predictor variables. In stepwise multivariate analyses, the significant predictors of compliance were substance abuse (odds ratio 3.69, confidence limits 1.07-12.71) and global psychosocial risk (odds ratio 3.76, confidence intervals 1.18-11.97). These findings suggest that pretransplant evaluation of psychosocial risk factors can identify patients with increased risk of postoperative noncompliance and morbidity.

Comparison of topical cyclosporin and dexamethasone for the treatment of chronic superficial keratitis in dogs

Thirty dogs with chronic superficial keratitis (CSK) were randomly assigned to treatment with 0.2 per cent cyclosporin ointment or 0.1 per cent dexamethasone drops. They were treated for six weeks and examined before and after three and six weeks of treatment, and then every three weeks without treatment until the lesions recurred. The regression of the disease during the treatment and the time to a recurrence after the cessation of treatment were determined. Changes in the size of the corneal lesions were measured by image analysis of photographs taken at each examination, and the severity of adnexal changes such as conjunctival hyperaemia was assessed by means of a scoring system. Clinical evaluations suggested that both drugs were equally effective as treatments for CSK and a statistical analysis showed that they had reduced the size of the lesions to the same extent at each examination. There was a significant increase in tear production, measured by the Schirmer tear test, during the treatment with cyclosporin.

Pharmacology of L-754,142, a highly potent, orally active, nonpeptidyl endothelin antagonist

L-754,142, (-)-N-(4-iso-propylbenzenesulfonyl)-alpha-(4-carboxyl-2-n-propy lphenoxy)-3,4- methylenedioxyphenylacetamide, is a potent nonpeptidyl endothelin antagonist (e.g., Ki: cloned human ETA = 0.062 nM: cloned human ETB = 2.25 nM), with high specificity for endothelin receptors. In vitro, L-754,142 is a potent antagonist of ET-1-induced phosphatidyl inositol hydrolysis in Chinese hamster ovary cells expressing cloned human endothelin receptors (IC50: hETA = 0.35 nM; hETB = 26 nM) and of ET-1 induced contractions in rabbit iliac artery rings (pA2 = 7.74) and rat aortic rings (pA2 = 8.7). In vivo, L-754,142 is a potent and specific antagonist of exogenously administered ET-1 or big ET-1, L-754,142 fully protects against ET-1-induced lethality in mice (AD50 = 0.26 mg/kg i.v.). The pressor response to big ET-1 in the anesthetized ferret is blocked by this compound with an ED50 value of 0.019 mg/kg i.v. L-754,142 also blocks the pressor response to big ET-1 in the conscious rat with ED50 values of 0.30 mg/kg i.v. and 0.56 mg/kg p.o. The duration of action of L-754,142 in this rat model is more than 12 hr after an oral dose of 3 mg/kg. In summary, L-754,142 is a potent, orally active ET antagonist with a long duration of action in several in vivo models.

De novo solid malignancies after cardiac transplantation

BACKGROUND

As long-term survival after cardiac transplantation improves, neoplastic complications are increasingly being discovered. Although lymphoproliferative disorders predominate, the incidence and clinical spectrum of solid tumors in a uniform population of heart transplant recipients remains uncertain.

METHODS

We reviewed our experience with 712 patients who underwent cardiac transplantation. Clinical charts were reviewed and telephone interviews were conducted, when possible.

RESULTS

De novo solid malignancies were identified in 3.3% of patients at risk (21 of 633 patients). Twenty patients were male; mean age was 51.5 +/- 8.6 years. Most patients reported a significant smoking history. Pulmonary, urologic, and Kaposi's sarcoma were the most common malignancies identified. Mean interval from transplantation to diagnosis was 35 months. Six patients were diagnosed within 6 months of transplantation. One-year and 5-year survival after transplantation were 90% and 49%, respectively. One-year and 3-year survival after cancer diagnosis were 60% and 52%, respectively.

CONCLUSIONS

De novo solid malignancy after transplantation occurred with about half the frequency of lymphoproliferative disorders. A striking male predominance was noted. The interval from transplantation to the appearance of cancer is variable, and no clustering was identified. A significant smoking history warrants aggressive search for occult malignancy during pretransplantation evaluation of potential heart recipients.

Evolution of rifampin resistance in human immunodeficiency virus-associated tuberculosis

Acquired rifampin resistance without preexisting isoniazid resistance is highly unusual in patients with tuberculosis. The purpose of this report is to describe and characterize that unusual pattern of acquired drug resistance in three patients with human immunodeficiency virus (HIV) infection. The patients originally had Mycobacterium tuberculosis strains that were susceptible to isoniazid and rifampin. During treatment in two patients and after completion of therapy in the remaining one, each patient developed active, rifampin-resistant, isoniazid-susceptible tuberculosis. One patient subsequently developed isoniazid resistance also. Studies on patients' M. tuberculosis isolates using IS6110 restriction fragment length polymorphism typing and rpoB gene sequencing indicated that rifampin resistance in each patient arose during therapy by an rpoB gene mutation in the original M. tuberculosis isolate. Detection of this unusual drug-resistance phenotype in three patients with HIV infection suggests that acquired rifampin resistance is somehow associated with co-infection due to HIV and tuberculosis.

Influence of roughage and grain processing in high-concentrate diets on the performance of long-fed Holstein steers

The effects of roughage source and timing of inclusion in high-concentrate diets on feedlot performance were evaluated in each of 2 yr with 144 and 120 long-fed Holstein steers, respectively. Roughage, when included in the diet, was delivered in a built-in-roughage (BIR) pellet supplying 15 and 6% roughage (percentage of DM) or hay crop silage (HCS) supplying 7 and 10% roughage (percentage of DM) for the growing and finishing periods, respectively. The six dietary treatments (two pens each) investigated were continuous whole corn and pelleted supplement (no added roughage; WSC-PEL); BIR with cracked corn either in the growing (BIR-G) or finishing (BIR-F) period with whole corn being fed with pelleted supplement when BIR was not part of the diet; BIR and cracked corn fed continuously (BIR-CONT); and two HCS treatments in which the corn was fed either whole (HCS-WSC) or cracked (HCS-CSC) for the entire feeding period. Replicates were slaughtered 4 and 3 wk apart for yr 1 and 2, respectively. Pooled daily gains (yr 1 and 2) for the entire trial (1.39 to 1.45 kg/d) were not different (P > .05). Daily DM and concentrate intakes were lower (P < .001) and gain efficiency was higher (P < .001) for the WSC-PEL than for the other treatments. Carcass characteristics were similar among treatments except for an improved yield grade (P < .02) for the HCS treatments over the BIR treatments. The WSC-PEL treatment was the most profitable (+/steer) and the BIR-CONT diet was the least profitable. The HCS treatments were the most profitable of the roughage treatments. A newly proposed intake prediction equation for feedlot cattle performed similarly to the 1984 NRC equation with long-fed Holstein steer calves.

Preliminary findings of ophthalmological abnormalities in farmed halibut

Ocular abnormalities occurring in farmed halibut at the Sea Fish Industry Authority Marine Farming Unit, Ardtoe, Argyll were investigated clinically and post mortem. A significant number of fish were found to have posterior polar cystic changes either causing scleral ectasia or gross degenerative posterior segment abnormalities with chorioretinal atrophy. Other ocular abnormalities included cataract formation and intraocular inflammation. In a small number of fish gas bubble formation in the anterior chamber was observed during capture and examination. It is possible that the lesions seen in these fish are a form of gas bubble disease although super-saturation, the cause of gas bubble disease previously reported in farmed fish, does not occur in the tanks in which these fish are housed. While this paper provides no answers with regard to the aetiopathogenesis of the lesions, it is hoped that it will stimulate discussion, leading to resolution of these questions through a multidisciplinary approach to the problem.

Ethanol fixation of sputum sediments for DNA-based detection of Mycobacterium tuberculosis

The effect of ethanol fixation on PCR detection and viability of Mycobacterium tuberculosis in human sputum sediments was evaluated. M. tuberculosis seeded into sputum sediments was efficiently killed when treated for 1 h with 50, 70, or 95% ethanol. PCR amplification of a 123-bp fragment of the M. tuberculosis-specific IS6110 was not affected in ethanol-treated samples even when fixation was extended to 24 h. Ethanol fixation of sputum sediments did not affect the PCR detection of M. tuberculosis in clinical samples. PCR results from ethanol-treated clinical samples containing M. tuberculosis (smear positive and smear negative) or other respiratory pathogens correlated directly with the results by conventional detection methods for M. tuberculosis. Our results show that ethanol fixation of human sputum sediments containing M. tuberculosis significantly reduces the potential exposure of workers to viable M. tuberculosis without affecting DNA analysis by PCR. Also, ethanol fixation of sputum sediments provides a simple and inexpensive way to store and transport clinical specimens identified for DNA-based diagnostics without refrigeration.

Partial characterization of chitinolytic enzymes from Streptomyces albidoflavus

Streptomyces albidoflavus NRRL B-16746 secreted three types of chitinolytic enzymes: N-acetyl-glucosaminidase, chitobiosidase and endochitinase. Optimal activity for all three types of enzymes occurred at pH 4-6; however 55-74% of the chitobiosidase and endochitinase activity was detectable at pH 8-10. Chitobiosidase activity originated from two strongly acidic (pI < 3.0) proteins with molecular mass of 27 kDa and 34 kDa, while endochitinase activity originated from five major acidic proteins (pI 5.1, 5.3, 5.75, 5.8-5.9 and 6.4) with molecular mass of 59, 45, 38.5, 27 and 25.5 kDa. Purified chitobiosidases significantly reduced spore germination and germ tube elongation of Botrytis cinerea and Fusarium oxysporum. Chitinolytic enzymes with significant activity at pH 4-10 may be used, transgenically, to reduce the growth and/or development of a broad spectrum of insects and fungi that are major economic pests.

Comparison of the carbohydrate biological response modifiers Krestin, schizophyllan and glucan phosphate by aqueous size exclusion chromatography with in-line argon-ion multi-angle laser light scattering photometry and differential viscometry detectors

A major barrier to the development, preclinical and clinical application of natural carbohydrate biological response modifiers has been the difficulty involved in accurately characterizing carbohydrate polymers with molecular masses ranging from 10(4) to 10(7) g/mol. Herein, we employed size exclusion chromatography with multi-angle laser light scattering and differential viscometry to compare and contrast structural properties of the biological response modifiers Krestin, schizophyllan and glucan phosphate. Krestin, schizophyllan and glucan phosphate exhibit significant differences in molecular mass moments, molecular mass distribution, polymer sizes, intrinsic viscosity and perhaps their solution behaviour. This knowledge of precise physicochemical data is required for a better understanding of the properties and higher structure of complex carbohydrate biological response modifiers.

Relapse of Mycobacterium leprae infection with ocular manifestations

A case of ocular leprosy as the manifestation of persistent or relapsed Mycobacterium leprae infection approximately 20 years following treatment is reported. The clinical and pathological features of this case are described, and the molecular methods needed to arrive at the definitive diagnosis are examined. If blindness is to be averted, clinicians must have a high index of suspicion for the diagnosis of ocular leprosy when anterior segment changes are noted during ophthalmologic examination of a patient from an area in which M. leprae is endemic. The indolent nature of ocular leprosy may require lifelong surveillance and therapy to insure sight preservation.

Cell surface "blanket" of apolipoprotein E on rat adrenocortical cells

Apolipoprotein (apo) E is expressed at high levels by adrenocortical cells. In the present study, an affinity-purified antibody to rat apoE was used in combination with immunogold visualization at both the light and electron microscopic levels to determine the cellular and subcellular distribution of apoE within the rat adrenal cortex. At the light microscopic level, apoE was found primarily in z. fasciculata and z. reticularis with little or none detected in z. glomerulosa and medulla. Within the z. fasciculata and z. reticularis, apoE was present in the cytoplasm of all parenchymal cells. ApoE also was found on the cell surface both on the sinusoidal front and in regions well removed from the subendothelial space. Electron microscopic examination of the z. fasciculata showed that apoE on the sinusoidal front was on the parenchymal cell surface but not the endothelial cell. Cell surface apoE was prominent on microvilli as well as non-microvillar regions of plasma membrane in the subendothelial space. ApoE was also associated with the cell surface in intercellular spaces continuous with but well removed from the subendothelial space. These findings at the light and electron microscopic levels suggest that the z. fasciculata cell is encircled or covered with apoE on all faces of the cell. These results are consistent with the idea that this cell surface "blanket" of apoE participates in the uptake of lipoprotein cholesterol by either the endocytic or selective uptake pathways.

Direct genotypic detection of Mycobacterium tuberculosis rifampin resistance in clinical specimens by using single-tube heminested PCR

Recent analysis of the gene encoding the beta subunit of Mycobacterium tuberculosis RNA polymerase (rpoB) has demonstrated a small region that harbors the mutations most frequently associated with rifampin resistance. Earlier reports have described a high degree of sequence conservation of rpoB among mycobacteria other than M. tuberculosis and other GC-rich bacteria that can lead to false-positive amplification when applied directly to clinical specimens. We developed reagents for PCR amplification that are based on signature nucleotides discovered by comparative sequence analysis of the rpoB genes of organisms phylogenetically related to M. tuberculosis. The specificities of the reagents were challenged with 20 isolates of multiple-drug-resistant M. tuberculosis and more than 20 species of mycobacteria other than M. tuberculosis and other GC-rich organisms. A single-tube heminested PCR protocol was devised to obtain sensitivity equal to those of an IS6110-based PCR assay and culture in spiked sputum experiments. The assay correctly identified 21 of 24 (87.5%) culture-positive specimens, 13 of which were acid-fast smear-negative, in a panel of 51 clinical specimens. Three specimens that were false-positive initially were negative upon repeat testing when the assay was modified to eliminate the potential for aerosol carryover of the first-round amplification product during the open-tube addition of the second set of reaction reagents. This assay is the most sensitive and specific test to date for the direct detection of M. tuberculosis rpoB in clinical specimens. This rapid PCR-based assay can be used for the simultaneous identification of M. tuberculosis and its rifampin susceptibility genotype.

Rapid identification of a point mutation of the Mycobacterium tuberculosis catalase-peroxidase (katG) gene associated with isoniazid resistance

The complete catalase-peroxidase (katG) gene DNA sequence was determined for 15 strains of Mycobacterium tuberculosis with a wide range of susceptibility to isoniazid. Five of 9 strains with isoniazid MICs > or = 1.0 microgram/mL had one or more missense mutations and all 5 strains had a common G-->T transversion in codon 463, causing the replacement of arginine with leucine and the loss of an NciI or MspI restriction site. None of 6 strains with an isoniazid MIC < 1.0 microgram/mL had mutations affecting codon 463. Restriction analysis of 43 strains with isoniazid MICs > or = 1.0 microgram/mL showed that 19 (44.2%) had lost the NciI-MspI restriction site at the locus of codon 463 while only 1 of 32 strains with isoniazid MICs < or = 1.0 microgram/L had this restriction polymorphism. These results indicate that the mutation arginine-->leucine in codon 463 of the catalase-peroxidase gene occurs in a significant fraction (44.2%) of M. tuberculosis strains with isoniazid MICs > or = 1.0 microgram/mL.

NO, nitrosonium ions, nitroxide ions, nitrosothiols and iron-nitrosyls in biology: a chemist's perspective

The multiplicity of biological functions thus far attributed to NO has led to suggestions that some effects might be mediated by other, related species instead. The radical nature of NO cannot account for its cytotoxicity, but its reaction with superoxide to form peroxynitite and highly reactive hydroxyl radicals may be important in this context. The ease with which NO can react with and destroy Fe-S clusters is also an important factor. Nitrosonium and nitroxide ions can be produced in vivo and will react under conditions that are physiologically relevant. Both could, in theory, serve in cell signalling or as cytotoxic agents. More direct experimental evidence for their involvement is needed before we can confidently assign them specific biological roles. In this article, Anthony Butler, Frederick Flitney and Lyn Williams discuss the chemistry of NO and related species.

Apolipoprotein (apo) B and apoII gene expression are both estrogen-responsive in chick embryo liver but only apoII is estrogen-responsive in kidney

Estrogen regulates the hepatic synthesis of a variety of proteins required for egg yolk production in oviparous vertebrates. In chickens, two of these proteins, apolipoprotein (apo) B and apoII, comprise the major protein components of specialized very low density lipoprotein particles that transport triacylglycerols and cholesterol to the developing egg yolk. In the adult, apoB is synthesized constitutively in liver, small intestine, and kidney but is estrogen-responsive only in the liver. In this work we have examined the embryonic expression of the apoB and apoII genes in yolk sac, liver, kidney, and small intestine. The 14 kb apoB mRNA was first detected at day 3 of development in vascular yolk sac, a tissue involved in the transfer of yolk lipids into the embryonic circulation. Constitutive apoB mRNA expression was detectable in liver at day 6.5 and in kidney at day 7.5, but in intestine was barely detectable before hatching. The hepatic apoB gene acquired estrogen-responsiveness at day 6.5 and its hormone-dependent expression increased throughout development in concert with the estrogen-responsive expression of the apoII gene. In contrast, the constitutively expressed apoB gene in kidney remained unresponsive to estrogen. Surprisingly, the apoII gene was found to be responsive to estrogen in both the embryonic kidney and small intestine. ApoII mRNA induction by estrogen in kidney at day 11 was at 10% of the level in the liver but estrogen-responsiveness decreased later in development and was low in the adult.(ABSTRACT TRUNCATED AT 250 WORDS)

Characterization of rifampin-resistance in pathogenic mycobacteria

The emergence of rifampin-resistant strains of pathogenic mycobacteria has threatened the usefulness of this drug in treating mycobacterial diseases. Critical to the treatment of individuals infected with resistant strains is the rapid identification of these strains directly from clinical specimens. It has been shown that resistance to rifampin in Mycobacterium tuberculosis and Mycobacterium leprae apparently involves mutations in the rpoB gene encoding the beta-subunit of the RNA polymerases of these species. DNA sequences were obtained from a 305-bp fragment of the rpoB gene from 110 rifampin-resistant and 10 rifampin-susceptible strains of M. tuberculosis from diverse geographical regions throughout the world. In 102 of 110 rifampin-resistant strains 16 mutations affecting 13 amino acids were observed. No mutations were observed in rifampin-susceptible strains. No association was found between particular mutations in the rpoB gene and drug susceptibility patterns of multidrug-resistant M. tuberculosis strains. Drug-resistant M. tuberculosis strains from the same outbreak and exhibiting the same IS6110 DNA fingerprint and drug susceptibility pattern contained the same mutation in the rpoB gene. However, mutations are not correlated with IS6110 profiling outside of epidemics. The evolution of rifampin resistance as a consequence of mutations in the rpoB gene was documented in a patient who developed rifampin resistance during the course of treatment. Rifampin-resistant strains of M. leprae, Mycobacterium avium, and Mycobacterium africanum contained mutations in the rpoB gene similar to that documented for M. tuberculosis. This information served as the basis for developing a rapid DNA diagnostic assay (PCR-heteroduplex formation) for the detection of rifampin susceptibility of M. tuberculosis.

Clinical trial of fusidic acid for lepromatous leprosy

Fusidic acid was assessed for antileprosy activity in nine lepromatous leprosy patients. Patients received fusidic acid at either 500 mg/day for 12 weeks or 750 mg/day for 4 weeks followed by 500 mg/day for 8 weeks. All patients showed time-dependent clinical improvement and decreases in bacillary morphological index, radiorespirometric activity and PCR signal, and in serum phenolic glycolipid I. Fusidic acid appears to be a weakly bactericidal antileprosy agent which may have a role in the multidrug treatment of leprosy pending an evaluation of lepra-reaction-suppressive activity.