Current microbiological status of 'health foods' sold in Canada

A follow-up survey was conducted across Canada to evaluate the current status of 'health foods' sold in Canada. A total of 1239 sample units of 'health foods' were analysed for a variety of bacteria, including aerobic colony counts (ACC), coliforms, aerobic and anaerobic sporeformers, Escherichia coli and Bacillus cereus. Results presented indicate that 16.8-18.4% of the 'health foods' exceed ACC guidelines, 16.0-17.8% exceeded coliform guidelines, 35.7% exceeded aerobic sporeformer guidelines, 81.4% exceeded anaerobic sporeformer guidelines, and 9% exceeded B. cereus guidelines. Some ACC were further identified and found to be opportunistic pathogens, including the genera Bacillus, Enterococcus, and Staphylococcus. It was concluded that more extensive surveillance of this industry by health officials is needed.

New method for detection of a bronchopleural fistula: direct instillation of Tc-99m DTPA into the pleural space via a thoracostomy tube

A 65-year-old man who had undergone a right upper lobectomy for squamous cell carcinoma developed a persistent air space in the right superior thorax. Because a bronchopleural fistula was suspected, a new technique to demonstrate the fistula was used. Five mCi of Tc-99m DTPA was instilled through a pigtail catheter into the cavity. Radiotracer activity extended into the remaining right bronchial tree, trachea, and left bronchial tree on the 10 minute delayed image confirming the presence of a bronchopleural fistula. Using bronchoscopic guidance, the fistula was sealed with a fibrin plug. A repeat examination 4 days later revealed no extension of tracer from the cavity up to 60 minutes after instillation, indicating successful sealing of the fistula. This technique offers a rapid, inexpensive, and portable diagnosis of bronchopleural fistula.

Abscisic acid signaling through cyclic ADP-ribose in plants

Abscisic acid (ABA) is the primary hormone that mediates plant responses to stresses such as cold, drought, and salinity. Single-cell microinjection experiments in tomato were used to identify possible intermediates involved in ABA signal transduction. Cyclic ADP-ribose (cADPR) was identified as a signaling molecule in the ABA response and was shown to exert its effects by way of calcium. Bioassay experiments showed that the amounts of cADPR in Arabidopsis thaliana plants increased in response to ABA treatment and before ABA-induced gene expression.

Signaling functions of the tyrosine residues in the betac chain of the granulocyte-macrophage colony-stimulating factor receptor

The granulocyte-macrophage colony-stimulating factor (GM-CSF) receptor (GMR) is a heterodimeric receptor expressed by myeloid lineage cells. Binding of GM-CSF activates at least one receptor-associated tyrosine kinase, JAK2, and rapidly induces tyrosine phosphorylation of the GMR betac-chain (GMRbeta), but not the GMR alpha-chain (GMRalpha). To examine the role of GMRbeta tyrosine phosphorylaiton, each of the 8 tyrosine residues in the cytoplasmic domain of the human GMRbeta was mutated to phenylalanine (GMRbeta-F8), and this mutant receptor was expressed with wild-type GMRalpha in the interleukin-3-dependent murine hematopoietic cell line, Ba/F3. GM-CSF induced tyrosine phosphorylation of multiple cellular proteins in cells expressing GMRbeta-F8 , including JAK2 and STAT5. However, GM-CSF-induced tyrosine phosphorylation of both SHP2 and SHC was reduced or absent compared with wild-type. Next, a series of 8 receptors were generated, each containing only a single, restored, tyrosine residue. Tyrosine 577 was found to be sufficient to regenerate GM-CSF-dependent phosphorylation of SHC, and any of Y577, Y612, or Y695 was sufficient to regenerate GM-CSF-inducible phosphorylation of SHP2. Despite the signaling defect to SHC and SHP2, Ba/F3 cells expressing GMRbeta-F8 were still able to proliferate in response to 10 ng/mL of human GM-CSF, although mitogenesis was impaired compared with wild-type GMRbeta, and this effect was even more prominent at lower concentrations of GM-CSF (1 ng/mL). Overall, these results indicate that GMRbeta tyrosine residues are not necessary for activation of the JAK/STAT pathway or for proliferation, viability, or adhesion signaling in Ba/F3 cells, although tyrosine residues significantly affect the magnitude of the response. However, specific tyrosine residues are needed for activation of SHC and SHP2.

A new in utero model for lateral facial clefts

The etiopathogenesis behind the formation of atypical craniofacial facial clefts remains unknown. To test the hypothesis that physical restricting forces such as amniotic bands can lead to the formation of these unusual clefts in the postorganogenesis period, we have modified a previously reported fetal lamb model of amniotic band syndrome to examine the effects of these bands on craniofacial development. Five 70-day gestation fetal lambs (term, 140 days) were exposed via a maternal hysterotomy. In each animal, an attempt was made to create a lateral craniofacial cleft by applying a 2-0 nylon suture as a constriction band to the growing face. The sutures were attached to either the zygomatic arch or the infraorbital rim externally and then looped circumferentially into the oral commissure. Each suture was positioned so as to create either a Tessier type 5 or a Tessier type 7 cleft. Four of five fetal lambs survived to term. Both types of lateral facial clefts were effectively produced using this model. In each group, the presence of an intraoral constriction band led to the formation of macrostomia, with an average 7.4-mm lateral displacement of the oral commissure. In addition to these soft tissue changes, each animal also had partial bony clefting (i.e., a bony groove) induced by the pressure of the restriction band across the growing facial skeleton. In the two lambs with the Tessier type 7 cleft, incomplete bony clefts developed across the zygomatic arch. In three animals with bands placed across the medial infraorbital rim, significant infraorbital and malar bony clefts formed similar to a classic Tessier type 5 facial cleft. No evidence of tissue necrosis, maceration, or ulceration was noted in any animal. These data present, for the first time, evidence that the constriction of craniofacial growth by external forces such as a swallowed amnionic band can lead to the development of lateral facial clefting involving both soft tissue and bony elements. These malformations are likely due to a combination of directly tethering normal tissue migration and an increase in local pressure, which produces cellular ischemia and apoptosis. Furthermore, our data demonstrate that these clefts can occur later in fetal development during a period of facial growth rather than during the period of primary facial morphogenesis.

Australian bat lyssavirus infection in three fruit bats from north Queensland

We report the case findings of Australian bat lyssavirus infection in two black flying foxes (Pteropus alecto) and one little red flying fox (Pteropus scapulatus) from north Queensland between January 1995 and August 1996. Although the P. alecto case in January 1995 is the first recognised case of Australian bat lyssavirus infection in Australia, this was a retrospective diagnosis made after identification of the index case at Ballina in May 1996. Eight persons had exposure to the three bats. Serum antibodies to classical rabies virus were measured in six of these persons; the only one seropositive was a veterinarian who had previously been vaccinated against rabies. Six persons received rabies vaccine following exposure. None of the in-contact humans developed signs of lyssavirus infection. For people exposed to Australian bat lyssavirus-positive bats who have not been scratched or bitten or had mucosal contamination by these bats, we suggest a post-exposure regime of five inoculations of the human diploid cell inactivated rabies vaccine.

Identification of a novel human Rho protein with unusual properties: GTPase deficiency and in vivo farnesylation

We have identified a human Rho protein, RhoE, which has unusual structural and biochemical properties that suggest a novel mechanism of regulation. Within a region that is highly conserved among small GTPases, RhoE contains amino acid differences specifically at three positions that confer oncogenicity to Ras (12, 59, and 61). As predicted by these substitutions, which impair GTP hydrolysis in Ras, RhoE binds GTP but lacks intrinsic GTPase activity and is resistant to Rho-specific GTPase-activating proteins. Replacing all three positions in RhoE with conventional amino acids completely restores GTPase activity. In vivo, RhoE is found exclusively in the GTP-bound form, suggesting that unlike previously characterized small GTPases, RhoE may be normally maintained in an activated state. Thus, amino acid changes in Ras that are selected during tumorigenesis have evolved naturally in this Rho protein and have similar consequences for catalytic function. All previously described Rho family proteins are modified by geranylgeranylation, a lipid attachment required for proper membrane localization. In contrast, the carboxy-terminal sequence of RhoE predicts that, like Ras proteins, RhoE is normally farnesylated. Indeed, we have found that RhoE in farnesylated in vivo and that this modification is required for association with the plasma membrane and with an unidentified cellular structure that may play a role in adhesion. Thus, two unusual structural features of this novel Rho protein suggest a striking evolutionary divergence from the Rho family of GTPases.

Enhanced intracoronary thrombolysis with urokinase using a novel, local drug delivery system. In vitro, in vivo, and clinical studies

BACKGROUND

Current pharmacological regimens for treating intracoronary thrombus in the cardiac catheterization laboratory generally involve the administration of thrombolytic agents that result in a systemic fibrinolytic state and/or require prolonged arterial drug infusion. The purpose of the present study was to assess a new technique for treating intracoronary thrombus consisting of the local infusion of limited quantities of urokinase with a novel drug delivery device.

METHODS AND RESULTS

THe Dispatch coronary infusion catheter is a new local drug delivery system that allows for the prolonged infusion of therapeutic agents at an angioplasty site while distal coronary flow is maintained. Three experimental protocols were performed to determine the in vitro, in vivo, and clinical efficacy of this device. First, in vitro thrombolysis of fresh, porcine thrombus trapped in a 4-mm plastic tube with a 50% constriction and perfused with 20% porcine plasma was measured. Twenty-three thrombi were weighed before and after no treatment (n = 5), "systemic" urokinase administration (n = 4), local infusion of 150,000 U urokinase with a standard end-hole catheter (n = 4), local infusion of saline with the Dispatch catheter (n = 5), and local infusion of 150,000 U urokinase with the Dispatch catheter (n = 5). Second, 25 porcine coronary arteries in 23 pigs were dilated in vivo with conventional balloon angioplasty and then treated with 123I-labeled urokinase that was administered either by the Dispatch catheter (150,000 U; n = 16), intravenous systemic bolus (1,000,000 U; n = 3), guiding catheter infusion (500,000 U; n = 3), or local end-hole catheter infusion (150,000 U; n = 3). All vessels were subsequently harvested to quantify intramural deposition and subsequent washout of urokinase at the angioplasty site. Finally, 19 patients with angiographic evidence of intracoronary thrombus were treated with local urokinase infusion with the Dispatch catheter either before or after balloon angioplasty or directional atherectomy. In vitro studies demonstrated that infusion of urokinase with the Dispatch catheter decreased thrombus weight by 66% compared with no treatment (-25%), "systemic" urokinase administration (25%), end-hole catheter urokinase infusion (32%), or infusion of saline by the Dispatch catheter (32%) (P < or = .005). In vivo studies demonstrated immediate deposition of 0.12% of the urokinase delivered by the Dispatch catheter to the angioplasty site, compared with 0.0007% with systemic bolus, 0.003% with guiding catheter infusion, and 0.007% with local infusion with an end-hole catheter (P < .001). Urokinase deposited by the Dispatch catheter persisted intramurally for at least 5 hours. Patient studies demonstrated reduction of thrombus-containing stenoses and complete disappearance of intracoronary thrombus in all cases in which 150,000 U urokinase was locally infused over 30 minutes. There was no evidence of abrupt closure, distal embolization, or no reflow in any patient.

CONCLUSIONS

Local urokinase delivery with the Dispatch catheter can result in rapid and complete intracoronary thrombolysis using substantially less drug than standard thrombolytic techniques. Intramural deposition of drug with this technique creates a local reservoir of urokinase that may provide prolonged thrombolytic activity at the infusion site.

p190 RhoGAP, the major RasGAP-associated protein, binds GTP directly

In mitogenically stimulated cells, a specific complex forms between the Ras GTPase-activating protein (RasGAP) and the cellular protein p190. We have previously reported that p190 contains a carboxy-terminal domain that functions as a GAP for the Rho family GTPases. Thus, the RasGAP-p190 complex may serve to couple Ras- and Rho-mediated signalling pathways. In addition to its RhoGAP domain, p190 contains an amino-terminal domain that contains sequence motifs found in all known GTPases. Here, we report that p190 binds GTP and GDP through this conserved domain and that the structural requirements for binding are similar to those seen with other GTPases. While the purified protein is unable to hydrolyze GTP, we detect an activity in cell lysates that can promote GTP hydrolysis by p190. A mutated form of p190 that fails to bind nucleotide retains its RasGAP binding and RhoGAP activities, indicating that GTP binding by p190 is not required for these functions. The sequence of p190 in the GTP-binding domain, which shares structural features with both the Ras-like small GTPases and the larger G proteins, suggests that this protein defines a novel class of guanine nucleotide-binding proteins.

Ureaplasma diversum as a cause of reproductive disease in cattle

This article includes a brief review of the classification, habitat, and characteristics of the ureaplasmas, followed by a discussion of the pathogenesis, transmission, clinical syndromes, diagnosis, immunity, and treatment of Ureaplasma diversum infections in cattle.

The rice bZIP transcriptional activator RITA-1 is highly expressed during seed development

Systematic protein-DNA binding studies have shown that plant basic leucine zipper (bZIP) proteins exhibit a differential binding specificity for ACGT motifs. Here, we show that the rice transcription activator-1 (RITA-1) displays a broad binding specificity for palindromic ACGT elements, being able to bind A-, C-, and G-box but not T-box elements. By using gel mobility shift assays with probes differing in sequences flanking the hexameric core, we identified high-affinity A-, C-, and G-box binding sites. Quantitative and competition DNA binding studies confirmed RITA-1 specificity for these sites. Using rice protoplasts as a transient expression system, we demonstrated that RITA-1 can transactivate reporter genes possessing high-affinity but not low-affinity RITA-1 binding sites. Our results established a direct relationship between in vivo transactivation and in vitro binding activity. Transient expression assays that demonstrated the ability of RITA-1 to transactivate a construct containing rita-1 5' flanking sequences suggest that the factor may be autoregulated. Histochemical analysis of transgenic rice plants showed that a rita-1-beta-glucuronidase transgene is expressed in aleurone and endosperm cells of developing rice seeds. We propose that RITA-1 plays a role in the regulation of rice genes expressed in developing rice seeds.

An unusual pattern of metastases from Merkel cell carcinoma

An unusual case of Merkel cell carcinoma is presented in which the time course to development of nodal and haematogenous metastases was protracted and the predominant site of metastatic disease was small bowel.

A comparison of six different plating media used in the isolation of Salmonella

Seventeen Canadian Federal, Provincial and Public Health Laboratories took part in different phases of a comparative/collaborative study that evaluated rapid methods to the standard Health Protection Branch (HPB) method for the detection of Salmonella. A variety of commercial media were tested, including Brilliant Green Sulpha Agar, Bismuth Sulphite Agar, Hektoen Enteric Agar, Xylose Lysine Deoxycholate Agar, EF-18 Agar and Rambach Agar. Each laboratory compared up to six of these different plating media. Plating of 123 salmonellae cultures and 28 artificially-inoculated foods showed the recovery of Salmonella spp. on the six plating media to be within one log. Therefore, quantitative testing of the media showed them to be comparable in the recovery of salmonellae. Qualitative testing of the six media during the comparative/collaborative study of various methods showed that EF-18 Agar recovered the greatest number of isolates. Hektoen Enteric Agar ranked second, with the other agars being comparable in their recovery of Salmonella spp. Problems with the various media are summarized. Based on our results and those of other researchers, it is recommended that Bismuth Sulphite Agar be compulsory and that at least one other agar be used for newly developed cultural procedures.

Neovascularization in clinical stage A testicular germ cell tumor: prediction of metastatic disease

Increased numbers of blood vessels (angiogenesis or neovascularization) in certain primary tumors correlates with an increased risk for metastatic disease. We therefore conducted a blinded review of the resected testicular germ cell tumors of 65 clinical stage A patients to evaluate the usefulness of angiogenesis in identifying those patients with clinically occult nodal metastases (pathological stage B). Angiogenesis was assessed in the primary tumors using an immunohistochemical stain for factor VIII-related antigen assay for quantitation of microvessel counts. Of 65 clinical stage A patients, 43 had pathological stage B disease at retroperitoneal lymph node dissection. Eleven patients had microvessel counts > 30 microvessels/x 400 high powered field, and all of these patients had pathological stage B disease (P = 0.02 in univariate analysis). Multiple regression analysis using microvessel count and other histological findings found to be prognostic (venous invasion, lymphatic invasion, presence of embryonal carcinoma, and absence of yolk sac tumor) showed that only the absence of a yolk sac tumor component was significantly predictive of occult metastases. This study shows that angiogenesis, as measured by quantitation of microvessel counts in the primary tumor of germ cell neoplasms, is significantly predictive of occult nodal metastatic disease by univariate analysis in clinical stage A patients. The prospective use of angiogenesis quantitation needs to be defined.

Plant bZIP proteins gather at ACGT elements

ACGT cis-acting DNA sequence elements have been identified in a multitude of plant genes regulated by diverse environmental, physiological, and environmental cues. In vivo transient and transgenic plant expression studies have shown that these ACGT elements are necessary for maximal transcriptional activation. Plants possess a conserved family of DNA-binding proteins specific for these DNA sequence motifs. Well-defined in terms of nucleotide sequence required for protein/DNA interactions and transcriptional activation, various ACGT elements have been used as molecular probes to clone sequence-specific DNA binding proteins. All plant DNA-binding proteins specific for ACGT elements belong to the bZIP classification. Most recombinant bZIP proteins can interact with ACGT elements derived from different plant genes, albeit with different affinity. Systematic protein/DNA binding studies have shown that sequences flanking the ACGT core affect bZIP protein binding specificity. These studies have provided the basis for a concise ACGT nomenclature and defined high-affinity A-box, C-box, and G-box elements. Plant bZIP factors can be classified according to their quantitative binding affinities for high-affinity ACGT elements. Potential molecular mechanisms that may control how plant bZIP proteins activate plant gene expression are discussed.

Multiple SWI6-dependent cis-acting elements control SWI4 transcription through the cell cycle

The Saccharomyces cerevisiae SWI4 gene encodes an essential transcription factor which controls gene expression at the G1/S transition of the cell cycle. SWI4 transcription itself is cell cycle regulated, and this periodicity is crucial for the normal cell cycle regulation of HO and at least two of the G1 cyclins. Since the regulation of SWI4 is required for normal cell cycle progression, we have characterized cis- and trans-acting regulators of SWI4 transcription. Deletion analysis of the SWI4 promoter has defined a 140-bp region which is absolutely required for transcription and can function as a cell cycle-regulated upstream activating sequence (UAS). The SWI4 UAS contains three potential MluI cell cycle boxes (MCBs), which are known cell cycle-regulated promoter elements. Deletion of all three MCBs in the SWI4 UAS decreases the level of SWI4 mRNA 10-fold in asynchronous cultures but does not abolish periodicity. These data suggest that MCBs are involved in SWI4 UAS activity, but at least one other periodically regulated element must be present. Since SWI6 is known to bind to MCBs and regulate their activity, the role of SWI6 in SWI4 expression was analyzed. Although the MCBs cannot account for the full cell cycle regulation of SWI4, mutations in SWI6 eliminate the normal periodicity of SWI4 transcription. This suggests that the novel cell cycle-regulated element within the SWI4 promoter is also SWI6 dependent. The constitutive transcription of SWI4 in SWI6 mutant cells occurs at an intermediate level, which indicates that SWI6 is required for the full activation and repression of SWI4 transcription through the cell cycle. It also suggests that there is another pathway which can activate SWI4 transcription in the absence of SWI6. The second activator may also target MCB elements, since SWI4 transcription drops dramatically when they are deleted.

Plant bZIP protein DNA binding specificity

Plant bZIP proteins exhibit a relaxed DNA-binding specificity for DNA sequence motifs containing an ACGT core. Gel mobility shift experiments employing ten different recombinant plant bZIP proteins demonstrated that nucleotides flanking the ACGT core affected binding specificity and identified three different types of ACGT elements: G-box, CACGTG; C-box, GACGTC; and A-box, TACGTA, motifs. These ten different bZIP proteins could be categorized into three groups according to their qualitative and quantitative specificity for G-box and C-box elements. Dissociation constant values (Kd values) of these bZIP proteins for high affinity G-box and C-box elements and reciprocal competition gel mobility shift assays confirmed our classification scheme. Group 1 proteins exhibit a stronger binding affinity for G-box elements, group 2 proteins bind both G-box and C-box motifs with comparable binding affinity, whereas the group 3 proteins display a stronger binding affinity for C-box oligonucleotides. Studies using a panel of G-box and C-box oligonucleotides differing in their flanking sequences identified high affinity binding sites. All ten plant bZIP proteins examined, except TGA1a, exhibited type A G-box binding activity preferring class I G-box elements. In contrast to the situation observed for G-box elements, C-box motifs displayed a very much more stringent flanking nucleotide requirement for binding activity. Protein/DNA binding experiments using scanning mutants of a high affinity G-box element and G-box/C-box hybrid elements demonstrated that bZIP protein binding activity depends upon the affinity of protein dimer subunits for ACGT half-sites. Information provided by our systematic analysis of plant bZIP DNA binding specificity can be used to identify high affinity binding sites for the plant bZIP proteins studied here. Assuming that only high affinity bZIP binding sites are likely to function in vivo, identification of these sites will allow us to predict which genes are activated by a particular bZIP protein.

Novel electrochemical device for the detection of cholesterol or glucose

A thin-layer twin-electrode electrochemical cell in which the working and auxiliary electrodes are facing each other and which contains the appropriate enzyme and a mediator was used for the determination of cholesterol or glucose. A steady-state diffusion-controlled response was obtained for cholesterol whereas for glucose the response was limited by diffusion and kinetics. Simulation of the system showed that a steady-state response is obtained, in the absence of kinetic complications, after a time of 0.01 d2/Ds, where d is the distance between the two electrodes and D is the diffusion coefficient of the mediator. Linear plots of steady-state current versus concentration were obtained for cholesterol and glucose. The results were compared with those expected theoretically and a thin-layer capillary fill device is proposed.

An approach to training and retaining primary care physicians in rural Appalachia

The West Virginia School of Osteopathic Medicine (WVSOM) educated and retained more primary care physicians for practice in rural Appalachia than did any other U.S. medical school from 1978 through 1990. This article describes the most important methods used at WVSOM to place physicians in rural areas: (1) The school has a focused, achievable mission (to provide primary care physicians who are trained to meet the medical needs of rural Appalachia and to improve the health care of the rural Appalachian population) that is agreed upon by the administration, faculty, and students; (2) it participates in a multistate educational exchange program with a similar mission; (3) it emphasizes personalized and interactive recruiting, admission, and placement processes aimed to attract nontraditional, rural students; (4) it provides early and long-term clinical training in rural sites (both hospitals and physicians' offices); (5) it is dedicated primarily to the education of medical students rather than to research or other goals; and (6) it is a freestanding school in a rural environment. The authors state that although WVSOM is unusual in some respects, at least some of its methods may be useful to other medical schools as they seek to produce more primary care physicians for rural and other underserved areas.