Suppression of antigen-specific T cell proliferation by measles virus infection: role of a soluble factor in suppression

Measles virus infection causes a profound immunosuppression. The basis for this immunosuppression is not known. This immunosuppression could be due to virus acting directly on lymphoid cells, the production of an immunosuppressive viral product, or a lymphoid product. We have developed an antigen-specific T cell system to study measles virus-T-cell interactions. We demonstrate that as few as five infectious viral particles added to 1000 T cells results in profound inhibition of antigen-specific T cell proliferation. Supernates taken from measles virus-infected T cells suppress the proliferation of uninfected T cells. Measles-virus-infected HeLa or Vero cells do not produce the factor. The antiproliferative effects of the supernates cannot be attributed to infectious virus, IL-10 or TGF-beta. The soluble factor appears to be larger than 100 kDa, yet retains antiproliferative activity following trypsin digestion with a size less than 10 kDa. Loss of activity is seen following heat treatment at 56 degrees C. The factor is lymphoid cell specific and exhibits cytokine-like behavior yet appears not to be a known cytokine. This soluble factor may be responsible for the overt clinical immunosuppression seen in man and a previously undescribed cytokine induced by measles virus infection of human lymphocytes.

High-level dystrophin expression after adenovirus-mediated dystrophin minigene transfer to skeletal muscle of dystrophic dogs: prolongation of expression with immunosuppression

Replication-deficient adenovirus vectors (AdV) have been successfully used to transfer a truncated human dystrophin cDNA to skeletal muscle of dystrophin-deficient mdx mice. A dystrophin-deficient golden retriever dog model (GRMD) has been identified, which, unlike the mouse model, leads to a clinicopathological phenotype similar to that of Duchenne muscular dystrophy (DMD). We show for the first time that high-level dystrophin expression in skeletal muscle of GRMD dogs can be achieved by AdV-mediated gene transfer. However, a humoral and cellular immune response of the host against antigens of viral and transgene origin (similar to that occurring in mdx mice after AdV-mediated dystrophin gene transfer) leads to a decline of dystrophin expression over a 2-month period. Immunosuppression by cyclosporin significantly prolonged transgene expression. The GRMD model may help to solve the open questions pertaining to dystrophin gene transfer such as systemic delivery and improvement of muscle function before human trials for gene replacement therapy in DMD may be considered.

Direct dystrophin and reporter gene transfer into dog muscle in vivo

Bacterial beta-galactosidase cDNA was injected without lipofectin into 41 sites in dog muscle and expression was seen in 22 of them. The cDNA and lipofectin was injected into 35 similar sites and expression was seen in 21. Expression was seen in a maximum of 2.5% of muscle fibers and 23.21% of nonmuscle cells. A total of 106 muscle sites were injected with the minigene with and without lipofectin. In 4 of the 45 sites injected with the minigene without lipofectin human dystrophin was expressed around the periphery of 0.3% of the fibers. Bacterial beta-galactosidase cDNA was injected into the peritoneal cavity of 4 pups, 2 of which also received lipofectin. In all 4, expression was seen in liver, spleen, and mesenteric lymph node. In the 2 pups that received lipofectin, expression was also seen in the diaphragm, intercostal, and abdominal muscles of 1 and in the diagphragm and intercostal muscles of the other. These experiments show that human dystrophin transgene expression can be obtained in dog muscle. However, other methods will be required to increase the degree of expression before gene therapy trials can be undertaken.

Use of the dog model for Duchenne muscular dystrophy in gene therapy trials

Golden retriever muscular dystrophy (GRMD) is an excellent model for the study of the efficacy of gene therapy in dystrophin deficient myopathies for there are many similarities between affected dogs and Duchenne muscular dystrophy (DMD) in boys. GRMD is not caused by deletion mutation but results from a point mutation in the consensus splice acceptor in intron 6 of the canine dystrophin gene. As a result exon 7 is skipped during processing of the GRMD dystrophin messenger RNA. We have developed a rapid test which makes direct use of exon 7 specific genomic PCR products. We have undertaken preliminary experiments on gene therapy using the mini-gene and the full length gene alone and in combination with lipofectin and/or the bacterial beta-galactosidase reporter gene Lac Z. Following direct injection of the Lac Z plasmid, either alone or with lipofectin, about 50% of the sites showed expression when biopsied some 14 days later. The beta-galactosidase activity was present in muscle and granulation tissue but was never abundant. Pups injected intraperitoneally with Lac Z were found to have positive material in their mesenteric lymph nodes, liver and spleen. Those injected with Lac Z and lipofectin also had positive material in the diaphragm, intercostal muscles and abdominal muscles, but again only a small amount of positive material was present at any of the sites. In animals directly injected into the muscle with the dystrophin mini-gene, half had positive staining for dystrophin in biopsies taken 14 days later. Of the 6 sites in the muscles of animals given the mini-gene and lipofectin only one had fibres positive for dystrophin when examined 14 days later. Six pups were injected directly with full-length gene construct and when biopsies were taken 10 days later two of the animals had strongly stained peripheries to a small number of fibres.

Wound care

Soft-tissue injuries remain one of the most common problems encountered in the emergency department. This article discusses techniques to minimize pain during the evaluation and repair process, methods to decrease healing complications, and repair considerations.

Characterization of fatal beta blocker ingestion: a review of the American Association of Poison Control Centers data from 1985 to 1995

OBJECTIVE

To characterize beta blocker-related deaths.

METHODS

This is a retrospective review of beta blocker-related exposure data and fatality case abstracts reported to the American Association of Poison Control Centers Toxic Exposure Surveillance System during the 11 year period, 1985 to 1995. Historical and laboratory data were used to determine those fatalities which resulted primarily from beta blocker intoxication.

RESULTS

Of 52,156 reported beta blocker exposures, 164 were fatal. In 38 cases, beta blockers were implicated as the primary cause of death. Propranolol was responsible for the greatest number of exposures (44%) and implicated as the cause of death in a disproportionately high percentage of fatalities (71%). Patients were generally young women; 63% were female and 92% were less than 50 years old. The dysrhythmias most often noted in fatal cases were bradycardia and asystole. Cardiopulmonary arrest did not develop until patients were in the care of health care personnel in 59% of cases. Though glucagon was initiated more often than any other intervention in fatal intoxications (83%), optimal dosing and maintenance infusions appear to have been underutilized.

CONCLUSIONS

The predominance of fatalities associated with propranolol compared to other beta blockers reflects both its greater frequency of use over the time period studied and its greater toxicity. Since 59% developed. cardiac arrest after reaching health care personnel, further study should focus on identifying medical intervention that can reduce mortality in this group.

Glucagon therapy in the treatment of symptomatic bradycardia

Symptomatic bradycardia is commonly seen in the emergency department. Effective drug therapy for this clinical scenario is limited. Although glucagon has been used in no clinical trial in this setting, its cardiac activity may prove useful, particularly in the setting of beta-adrenergic blockade. We report a case series comprising three patients taking maintenance beta-blocker therapy who presented to the ED with symptomatic bradycardia and hypotension and in whom glucagon therapy obviated the need for further treatment. Further study is warranted to evaluate and define the role of glucagon in the treatment of symptomatic bradycardia.

Hemodynamic effects of calcium chloride in a canine model of acute propranolol intoxication

STUDY OBJECTIVE

To evaluate the hemodynamic effects of calcium chloride in a canine model of acute propranolol toxicity.

METHODS

Two minutes after the completion of a propranolol infusion (10 mg/kg), a bolus of .125 mL/kg 10% CaCl solution followed by an infusion of .375 mL/kg over the next 30 minutes or a bolus and subsequent infusion of an equivalent volume of normal saline solution was administered to each dog.

RESULTS

CaCl yielded significant improvements in propranolol-induced decreases in cardiac index and stroke volume compared with saline solution-treated control animals (overall alpha = .05). Furthermore, CaCl administration resulted in earlier improvement in propranolol-induced alterations in mean arterial pressure, maximal left ventricular pressure change over time, and peripheral vascular resistance compared with saline solution (overall alpha = .05). We observed no difference between treatment groups in response to propranolol-induced bradycardia or QRS-interval prolongation.

CONCLUSION

In this model of acute propranolol toxicity, CaCl therapy improved depressed hemodynamic status, mainly by a positive inotropic action.

Mutation segregation and rapid carrier detection of X-linked muscular dystrophy in dogs

OBJECTIVES

To use exon 7-specific genomic polymerase chain reaction (PCR) products to identify the genotypes of normal, affected, and carrier female dogs in pedigrees segregating Golden Retriever muscular dystrophy (GRMD), and to confirm the concordant segregation of the mutation in all carrier and affected dogs presently available.

DESIGN

The GRMD mutation is found in the consensus splice acceptor site in intron 6 of the canine dystrophin gene. PCR cycle-sequencing and restriction fragment length polymorphism/PCR were used for determination of the pattern of segregation of the point mutation which causes GRMD.

ANIMALS

Normal, clinically affected, and obligate carrier dogs in pedigrees of GRMD.

PROCEDURE

DNA from blood was amplified, using PCR and primers that bracket all of exon 7 of the canine dystrophin gene as well as 100 base pairs of intron on either side. PCR products were either cycle-sequenced directly or submitted to a second round of PCR, using 1 of the original primers coupled with a mutagenic restriction fragment length polymorphism-primer, which thus creates an artificial restriction site. Digestion with Stu I detected the normal allele. To detect the affected allele, Sau96 I was used to digest the 310-base pair exon 7 genomic fragment directly.

CONCLUSIONS

Simple, clear diagnosis of carrier status was possible using these methods. This mutation is passed through all carrier and affected dogs in both United States GRMD colonies and the colony in Australia.

CLINICAL RELEVANCE

Rapid, accurate diagnosis of carrier and affected dogs will enhance study of this homologue of Duchenne muscular dystrophy.

Level I trauma certification and emergency medicine resident major trauma experience

OBJECTIVE

American College of Surgeons (ACS) and Residency Review Committee for Emergency Medicine (RRC-EM) guidelines conflict regarding the role of emergency physicians in directing major trauma resuscitations. This article describes the impact of ACS level I trauma certification on emergency medicine (EM) resident trauma experience.

METHODS

A written survey and a follow-up letter were sent to all 101 EM program directors as of August 16, 1994. The survey addressed demographics and trauma experience at hospitals designated by the RRC-EM as primary training sites.

RESULTS

There were 95 (94%) survey respondents. Estimates of the percentage of trauma resuscitations directed by EM residents were significantly lower at level I centers (52% +/- 27%, 95% CI 45-59%) than they were at non-level I centers (70% +/- 30%, 95% CI 58-82%) (p < 0.01). There was no significant difference in trauma census between level I and non-level I centers. Of 14 respondents who said they were cited by the RRC-EM for inadequate trauma experience, ten (71%) were in ACS level I trauma centers (p = 1.0). Twelve of the 14 respondents cited for inadequate trauma experience were in either the Northeast or the Midwest.

CONCLUSIONS

EM residents direct a smaller percentage of major trauma resuscitations at ACS level I hospitals than they do at non-level I facilities. This finding is not offset by an increased trauma census at level I facilities and may be more pronounced in the Northeast and the Midwest.

Acute myocardial infarction and congestive heart failure

The effective treatment of patients with acute myocardial infarction (AMI) and acute congestive heart failure (CHF) requires quick triage, accurate identification, and appropriate pharmacologic management. This article describes the initial assessment and management of adult patients with AMI and CHF, beginning with the first interaction of such patients with the emergency department staff.

Comparison of tensile strength of cyanoacrylate tissue adhesive closure of lacerations versus suture closure

STUDY OBJECTIVE

To compare the tensile strength of lacerations closed with cyanoacrylate tissue adhesive, with suture, and with a combination of tissue adhesive and suture.

DESIGN

Randomized, controlled animal model study.

SETTING

Animal care facility.

PARTICIPANTS

Sixteen albino guinea pigs.

INTERVENTIONS

Four incisions to deep fascia were created on the dorsum of each animal. Lacerations were closed with either tissue adhesive alone, tissue adhesive with subcutaneous suture, percutaneous suture alone, or percutaneous suture with subcutaneous suture. After 4 days, the breaking strengths of all wound closures were measured.

RESULTS

Wound closures made with cyanoacrylate tissue adhesive alone exhibited significantly less tensile strength at 4 days than closures made by the other three methods. Wound closures made with combined percutaneous and subcutaneous sutures were significantly stronger than all other groups.

CONCLUSION

Wound closures made with cyanoacrylate tissue adhesive alone have less tensile strength at 4 days than those made with tissue adhesive and subcutaneous suture or those closed by traditional suture methods.

Evidence of molecular heterogeneity for generalised glycogenosis between and within breeds of cattle

Northern analyses revealed normal levels of acidic alpha-glucosidase mRNA in cultured fibroblasts from a Shorthorn calf affected with glycogenosis but a gross deficiency in an affected Brahman calf. Analyses of acidic alpha-glucosidase activity, relative to that of other lysosomal enzymes, in blood mononuclear cells revealed greater variation within and between Brahman herds than Shorthorn herds. A Msp1 restriction fragment length polymorphism associated with glycogenosis in Brahmans was not found in Shorthorns. These results are considered in relation to molecular heterogeneity for AAG deficiency in cattle and its implications for disease control programs.

Host response to multiple skin lacerations on the albino guinea pig

Investigators have studied methods of treating skin lacerations by placing multiple incisions on each albino guinea pig. Theoretically, host responses to laceration sites may differ on the basis of anatomic location and local cytokine effects. We used cytokine values and histologic examination to identify differences when multiple lacerations were placed on each animal. Four 3-cm lacerations were made on the dorsum of each male albino guinea pig: two incisions on either side and parallel to the spine. Each laceration was closed with staples. In five animals a sponge technique was used to assay wound cytokines 48 h later. In an additional four animals, wounds were excised at 96 h and stained for cells and new collagen. We identified no statistically significant differences among laceration sites based on polymorphonuclear and mononuclear cellularity, number of fibroblasts, new collagen deposition, or wound interleukin (IL)-6 activities. Using this model minimizes the number of animals needed to generate statistically significant findings in wound research.

Comparison of effects of suture and cyanoacrylate tissue adhesive on bacterial counts in contaminated lacerations

We studied the effects of closing lacerations with suture or cyanoacrylate tissue adhesive on staphylococcal counts in inoculated guinea pig lacerations. Wounds closed with adhesive alone had lower counts than wounds containing suture material (P < 0.05). The results of a time-kill study were consistent with a bacteriostatic adhesive effect of the adhesive against Staphylococcus aureus.

Infrared emission detection tympanic thermometry may be useful in diagnosing acute otitis media

To determine the utility of infrared emission detection (IRED) tympanic thermometry in diagnosing acute suppurative otitis media (ASOM), a prospective, nonblinded sampling of ear temperatures was performed. Children between the ages of 6 months and 6 years presenting to an urban emergency department were included in the study. Tympanic temperatures were determined in all subjects. Clinical data, tympanic audiometry, and telephone follow-up were used to define ASOM. Temperature differences were determined for children with unilateral ASOM and those without ear infection. Data from 48 patients were analyzed. The mean temperature difference in the control group, 0.23 degrees +/- 0.15 degrees C (95% confidence interval [CI], 0.17 degree to 0.29 degree C) differed from those with ASOM: 0.39 degree +/- 0.29 degree C (95% CI, 0.25 degree to 0.53 degree C, P = .047). Logistic regression was used to describe the predictive relationship between temperature difference and probability of ASOM. We conclude that IRED tympanic thermometry may be useful in diagnosing ASOM when used with other clinical data.