Methamphetamine overdose: experience with six cases

We describe experience with 6 cases of methamphetamine overdose. Because of its low cost, easy availability and longer duration of action compared to cocaine, methamphetamine has become the drug of choice in various communities. Marked change in mental status was observed in all of our patients. One patient had a myocardial infarction that responded well to thrombolytic therapy. Clinicians should be familiar with the medical effects and treatment of acute methamphetamine toxicity.

Determinants of preterm birth rates in Canada from 1981 through 1983 and from 1992 through 1994

BACKGROUND

The rates of preterm birth have increased in many countries, including Canada, over the past 20 years. However, the factors underlying the increase are poorly understood.

METHODS

We used data from the Statistics Canada live-birth and stillbirth data bases to determine the effects of changes in the frequency of multiple births, registration of births occurring very early in gestation, patterns of obstetrical intervention, and use of ultrasonographic dating of gestational age on the rates of preterm birth in Canada from 1981 through 1983 and from 1992 through 1994. All births in 9 of the 12 provinces and territories of Canada were included. Logistic-regression analysis and Poisson regression analysis were used to estimate changes between the two three-year periods, after adjustment for the above-mentioned determinants of the likelihood of preterm births.

RESULTS

Preterm births increased from 6.3 percent of live births in 1981 through 1983 to 6.8 percent in 1992 through 1994, a relative increase of 9 percent (95 percent confidence interval, 7 to 10 percent). Among singleton births, preterm births increased by 5 percent (95 percent confidence interval, 3 to 6 percent). Multiple births increased from 1.9 percent to 2.1 percent of all live births; the rates of preterm birth among live births resulting from multiple gestations increased by 25 percent (95 percent confidence interval, 21 to 28 percent). Adjustment for the determinants of the likelihood of preterm birth reduced the increase in the rate of preterm birth to 3 percent among all live births and 1 percent among singleton births.

CONCLUSIONS

The recent increase in preterm births in Canada is largely attributable to changes in the frequency of multiple births, obstetrical intervention, and the use of ultrasound-based estimates of gestational age.

Pigeon fanciers' lung: the mucin antigen is present in pigeon droppings and pigeon bloom

BACKGROUND

Pigeon intestinal mucin has been implicated as an important antigen pigeon fanciers' lung. This study investigated whether mucin is detectable in pigeon droppings and bloom, the likely antigenic sources in disease.

METHODS

Soluble extracts of a number of materials found in a pigeon loft were prepared and specific IgG subclass antibodies to these antigens were measured in 14 antibody-positive pigeon fanciers. Cross-reactivity between these materials and purified pigeon intestinal mucin was investigated by inhibition of anti-mucin ELISA. Mucin was purified from the soluble extracts of these crude antigen mixtures by CsCl density gradient centrifugation.

RESULTS

The patterns of IgG subclass responses to purified pigeon intestinal mucin and to the four materials collected from the pigeon loft were similar. Subclass differences between symptomatic and asymptomatic individuals, demonstrable against purified mucin, were similarly seen against pigeon droppings and pigeon bloom. Both pigeon droppings and pigeon bloom were capable of inhibiting IgG binding to purified pigeon mucin, and mucin inhibited substantially the binding of IgG to these materials. Glycoprotein with a density similar to that described for pigeon intestinal mucin was purified from each source.

CONCLUSION

Pigeon intestinal mucin is present in a variety of materials found in the environment of the pigeon loft in a form capable of reacting with anti-mucin antibodies in the sera of exposed individuals. Reduction in exposure to these materials may decrease the likelihood of developing pigeon fanciers' lung and minimise reactions in sensitised individuals.

Helicobacter pylori in vivo causes structural changes in the adherent gastric mucus layer but barrier thickness is not compromised

BACKGROUND

It has been proposed that a pathogenic effect of Helicobacter pylori is a weakening of the protective mucus barrier; however, this remains controversial.

AIMS

To clarify the effects of H pylori infection on the mucus gel barrier in vivo.

METHODS

Mucus gel polymeric structure and the thickness of the adherent mucus barrier were measured in endoscopic biopsy samples in subjects with and without H pylori infection.

RESULTS

There was a significant 18% reduction in the proportion of polymeric gel forming mucin in the adherent mucus layer in H pylori positive compared with negative subjects. There was no change in the adherent mucus thickness between H pylori positive and negative subjects without gastric atrophy (mean (SD): 104 (26) micron, 106 (30) micron, respectively). There was however a significant reduction in mucus thickness in those H pylori positive subjects with underlying gastric atrophy (84 (13) micron, p=0.03) compared with those without atrophy.

CONCLUSIONS

A partial breakdown in gel forming structure of the gastric mucus barrier does occur in H pylori infection per se but this is insufficient to cause a collapse of the mucus barrier.

A cost measurement study for a tele-oncology practice

The costs of providing oncology services in three different ways were measured. Services were provided to a peripheral hospital by: conventional clinics, in which the oncologist worked at the hospital concerned; outreach clinics, in which an oncologist was flown in periodically from a central hospital; telemedicine clinics, in which the oncologist at the central hospital practised via a video-link. During a one-year study period, 2400 patients were seen in conventional clinics, 81 in outreach clinics and 103 in telemedicine clinics. At these workloads the average costs per patient were $149, $897 and $812, respectively. However, the average costs cannot be compared directly without further information about the shape of the unit cost curves.

The MUC2 gene product: a human intestinal mucin

The MUC2 gene product is the first human secretory mucin protein core to be fully sequenced. Like the other eight human MUC genes identified to date, MUC2 is characterised by tandem and irregular repeat sequences rich in threonine and serine, the potential sites of attachment of the oligosaccharide chains. The MUC2 gene product is more than 5100 amino acids in its commonest allelic form and accounts for one fifth by weight of the mucin glycoprotein molecule (80% oligosaccharide side chains). The MUC2 product is polymerised end to end through disulphide bridges to form large secreted polymeric gel-forming mucins (Mr approximately 10(7)). The primary function of the MUC2 gene product is to provide a protective barrier between the epithelial surfaces and the gut lumen. There is decreased expression of MUC2 in colonic cancer and defective polymerisation of secreted mucin in ulcerative colitis. Elucidation of the MUC2 and other mucin gene sequences has opened the way for a full structural characterisation and an improved understanding of the structure and function of these complex mucus gel secretions.

Pigeon fanciers' lung: effects of smoking on serum and salivary antibody responses to pigeon antigens

A reduced prevalence of pigeon fanciers' lung has been reported in pigeon breeders who smoke cigarettes. Serum and salivary antibodies to pigeon intestinal mucin and pigeon serum proteins were investigated in 227 pigeon fanciers, subdivided according to smoking habit and clinical status. Smokers had a lower incidence of precipitating antibodies to pigeon antigens and lower titres of serum IgG and IgA antibodies to mucin and to pigeon serum proteins in ELISA compared with non-smokers and ex-smokers. In contrast, IgG antibody titres to tetanus toxoid were similar in smoking and non-smoking groups. In contrast to serum antibodies, salivary IgA antibody titres to pigeon antigens were similar in smokers and non- or ex-smokers. Approximately one third of the smokers reported symptoms consistent with pigeon fanciers' lung but did not have precipitating antibodies. Only some individuals with precipitating antibodies had disease symptoms, and IgG antibody titres in these individuals were not significantly higher than in many asymptomatic individuals. Salivary IgA titres against pigeon mucin were significantly higher in asymptomatic individuals, consistent with a protective role for these antibodies. The results confirm that smoking is associated with a decreased serum antibody response to inhaled pigeon antigens, affecting IgG1, IgG2 and IgA responses, but this impairment does not extend to salivary IgA or to antibody responses to a parenterally administered protein antigen. The fact that responses to pigeon serum proteins and to pigeon intestinal mucin were similarly affected suggests that cigarette smoking depresses both T-independent and T-dependent responses to inhaled antigens.

Outcome of renal replacement therapy in antineutrophil cytoplasmic antibody-associated systemic vasculitis

Antineutrophil cytoplasmic antibody-associated systemic vasculitis (AASV) frequently leads to end-stage renal disease (ESRD). Potentially fatal disease activity can continue after the onset of ESRD in both dialysis and transplant patients, despite the immunosuppressive effects of uremia and rejection prophylaxis, leading to concerns that such patients have greater morbidity and mortality. To assess the outcome of AASV patients receiving renal replacement therapy, a retrospective analysis of 59 patients from our unit who received chronic dialysis, renal transplantation, or both, was performed. The survival of AASV patients with ESRD was comparable to national registry controls, as were both graft and patient survival after renal transplantation. Ther is no evidence that standard immunosuppressive protocols should be altered for AASV patients receiving renal transplants. The rate of relapse of vasculitis for patients on chronic dialysis and after transplantation was 0.09 and 0.02 per patient per year, respectively. These rates are lower than those of other series and support the contention that continued immunosuppression after ESRD, as practiced in our unit, is warranted. Relapses usually responded to cyclophosphamide and high-dose prednisolone treatment. Significantly, vasculitic flare-ups in dialysis patients were sometimes initially misdiagnosed as dialysis complications, leading to fatal delays in effective treatment. Follow-up by physicians experienced in the diagnosis and treatment of vasculitis activity should continue in these patients.

A novel method for the visualization of the in situ mucus layer in rat and man

1. The observed thickness of the gastric mucus barrier varies widely, even appearing discontinuous, depending on the methods used. Here we describe the development and application of a modified periodic acid Schiff/Alcian Blue staining technique for use on cryostat sections of gastric mucosa. This technique for the first time enables the preservation and visualization of the full thickness of the adherent gastric mucus layer and the underlying mucosa. 2. In designing this novel method we have selected those procedures which would result in the least alteration to the mucus layer. The methods used were snap freezing, cryostat sectioning of the whole stomach followed by brief ethanol pretreatment (10 min in 100% ethanol), a prolonged staining with periodic acid Schiff/Alcian Blue (15 min and 2.5 h respectively), a gentle post-fixation (45 min paraformaldehyde vapour at 37 degreesC) and the use of a water-soluble mountant. 3. A continuous, adherent mucus layer was observed over the surface of the rat gastric mucosa (periodic acid Schiff/Alcian Blue stained) and human gastric antral biopsies (periodic acid Schiff stained). In the rat the mean (S.D.) mucus thickness measurements along the antrum to oesophageal axis (which was divided histologically into four regions, A to D) were: A, 166 (47) micrometer; B, 179 (48) micrometer; C, 184 (50) micrometer; D (the non-glandular stratified epithelium at the top of the stomach), Absent. In human gastric antral biopsies the mean (S.D.) mucus thickness was 144 (52) micrometer. 4. This new technique has enabled the visualization and precise measurement of thickness of the gastric mucus layer in rat and man. The adherent gastric mucus layer was observed to be continuous in the rat glandular stomach and human antrum. In validation experiments in rat the mean mucus thickness measurements were found to be twice those measured by conventional histological techniques, in which the mucus layer appeared discontinuous and patchy. However, they were within the range of thickness values seen in unfixed tissues and in the rat in vivo preparation.

The MUC2 gene product: a human intestinal mucin

The MUC2 gene product is the first human secretory mucin protein core to be fully sequenced. Like the other eight human MUC genes identified to date, MUC2 is characterised by tandem and irregular repeat sequences rich in threonine and serine, the potential sites of attachment of the oligosaccharide chains. The MUC2 gene product is more than 5100 amino acids in its commonest allelic form and accounts for one fifth by weight of the mucin glycoprotein molecule (80% oligosaccharide side chains). The MUC2 product is polymerised end to end through disulphide bridges to form large secreted polymeric gel-forming mucins (Mr approximately 10(7)). The primary function of the MUC2 gene product is to provide a protective barrier between the epithelial surfaces and the gut lumen. There is decreased expression of MUC2 in colonic cancer and defective polymerisation of secreted mucin in ulcerative colitis. Elucidation of the MUC2 and other mucin gene sequences has opened the way for a full structural characterisation and an improved understanding of the structure and function of these complex mucus gel secretions.

A joint US-UK study of home telenursing

Nursing notes for patients nursed at home in the USA and the UK were reviewed using an abstraction instrument developed and tested in the US. More than 1700 episodes of patient care at home were reviewed: 906 in the US and 839 in the UK. Preliminary data suggest that in the US approximately 45% of home nursing visits could be done via telemedicine, while the figure is lower in the UK, less than 15%. Pilot trials of an analogue video-telephone in Kansas City and Belfast suggest that even relatively low-quality compressed video may be useful for home nursing. Clearly, there are differences between the two countries which merit further study, but there is evidence to suggest that telemedicine may have a role in the delivery of home health care.

From early wireless to Everest

Medical information has been transmitted using wireless technologies for almost 80 years. A "wired wireless" electronic stethoscope was developed by the U.S. Army Signal Corps in the early 1920's, for potential use in ship-to-shore transmission of cardiac sounds. [Winters SR. Diagnosis by wireless. Scientific American June 11, 1921, p. 465] Today, wireless is used in a wide range of medical applications and at sites from transoceanic air flights to offshore oil platforms to Mt. Everest. 'Wireless LANs' are often used in medical environments. Typically, nurses and physicians in a hospital or clinic use hand-held "wireless thin client" pen computers that exchange patient information and images with the hospital server. Numerous companies, such as Fujitsu (article below) and Cruise Technologies (www.cruisetech.com) manufacture handheld pen-entry computers. One company, LXE, integrates radio-frequency (RF) enhanced hand-held computers specifically designed for production use within a wireless LAN (www.lxe.com). Other companies (Proxim, Symbol, and others) supply the wireless RF LAN infrastructure for the enterprise. Unfortunately, there have been problems with widespread deployment of wireless LANs. Perhaps the biggest impediment has been the lack of standards. Although an international standard (IEEE 802.11) was adopted in 1997, most wireless LAN products still are not compatible with the equipment of competing companies. A problem with the current standard for LAN adapters is that throughput is limited to 3 Mbps--compared to at least 10 Mbps, and often 100 Mbps, in a hard-wired Ethernet LAN. An II Mbps standard is due out in the next year or so, but it will be at least 2 years before standards-compliant products are available. This story profiles some of the ways that wireless is being used to overcome gaps in terrestrial and within-enterprise communication.

IgG subclass responses to pigeon intestinal mucin are related to development of pigeon fanciers' lung

BACKGROUND

Pigeon fanciers' lung (PFL) is a form of extrinsic allergic alveolitis. Affected individuals produce antibodies to various pigeon antigens, and the resulting immune complexes are thought to initiate the disease. However, high antibody titres also occur in some asymptomatic individuals. Previously attention has focused on protein antigens, but we have recently identified pigeon intestinal mucin as a novel antigen in PFL.

OBJECTIVE

To determine the relationship between IgG subclass antibodies to pigeon intestinal mucin and the development of pigeon fanciers' lung.

METHODS

Sera were collected from 250 pigeon fanciers, who also completed a clinical questionnaire. Sera were screened for precipitating antibodies to pigeon serum and droppings. Individuals with symptoms and precipitating antibodies were considered to have classical PFL. Serum IgG and IgG subclass antibodies to pigeon intestinal mucin and pigeon serum proteins were investigated by quantitative enzyme-linked immunosorbent assay (ELISA).

RESULTS

Very high titres of IgG antibodies against pigeon mucin were found in all precipitin-positive individuals. A strong positive correlation was seen between titres of antibodies to mucin and to serum proteins, but this was not due to crossreactivity. No significant differences in IgG titres to either mucin or pigeon serum proteins were found between individuals with PFL and asymptomatic precipitin positive fanciers. IgG1 and IgG2 were the major subclasses of anti-mucin, with lower titres of IgG3. Patients with PFL had significantly higher titres of IgG1 to mucin than asymptomatic, precipitin-positive individuals. In contrast, no significant differences were seen between PFL and asymptomatic precipitin-positive sera with respect to the subclass titres against pigeon serum proteins.

CONCLUSION

The high titres of anti-mucin IgG in sera of all individuals with PFL, together with the finding that high IgG1 titres to mucin are associated with the development of disease confirm pigeon intestinal mucin as an important antigen in PFL.

High-affinity benzodiazepine antagonists reduce responding maintained by ethanol presentation in ethanol-preferring rats

In the present study, we examined two high-affinity and selective benzodiazepine (BDZ) receptor antagonists (ZK 93426, CGS 8216) in ethanol (EtOH)-preferring rats whose responding (i.e., lever pressing) was maintained by the presentation of EtOH. The in vivo actions of CGS 8216 (1-30 mg/kg) and ZK 93426 (5-75 mg/kg) were examined after intraperitoneal or oral administration. Flumazenil (10-40 mg/kg) was used as a reference BDZ antagonist. EtOH (10% v/v) and saccharin (0.05 g/v) solutions were concurrently available for 30 min each day under a two-lever fixed-ratio schedule in which four responses on one lever produced the EtOH solution and four responses on the other lever produced the saccharin solution. A 40 mg/kg intraperitoneal injection of flumazenil given on the first injection day (day 1) nonsignificantly reduced control levels of responding maintained by EtOH by 36%. No effects were observed 24 hr after drug administration (day 2). Oral administration of flumazenil was without effect. On day 1, intraperitoneal administration of CGS 8216 (1-20 mg/kg) and ZK 93426 (1-50 mg/kg) reduced control levels of responding maintained by EtOH by 44% to 73%; on day 2, EtOH maintained responding continued to be suppressed with the highest doses (> or = 20 mg/kg) suppressing control levels of responding by as much as 62%. Oral administration of higher doses of CGS 8216 (5-30 mg/kg) and ZK 93426 (10-75 mg/kg) reduced responding maintained by EtOH by as much as 54% to 84% of controls; however, no effects were seen on day 2. Only the highest intraperitoneal dose of ZK 93426 (50 mg/kg) suppressed responding maintained by saccharin. These findings demonstrate that some BDZ antagonists decrease responding maintained by EtOH. The findings suggest that certain BDZ antagonists may have potential as pharmacotherapies to prevent or decrease EtOH abuse in humans.