Clinical and Histologic Manifestations of a Novel Rectus Femoris Myotendinous Junction Injury in Rats.

Background: Animal models of muscle injury have primarily relied on methods which do not mimic the chronic scarring that typically occurs adjacent to the myotendinous junction (MTJ). The goal of this study was three-fold: (i) to create a strain-induced in vivo model of rectus femoris MTJ injury in rats; (ii) to document clinical manifestations of injury using longitudinal tracking of individual animals via voluntary and compulsory (treadmill) mobility analyses and (iii) to validate and assess the model for persistent scarring through serial histologic assessment and development of a semi-quantitative grading scheme to characterize injury response over time. Methods: Strain-induced MTJ injury was generated in male Sprague Dawley rats via needle tension directed along the transverse axis between the rectus femoris muscle and distal tendon that attaches to the patella. Animals received mobility assessments (gait analysis using a DigiGait Treadmill System and weight bearing using a Tekscan Rodent Walkway System) at days 0, 1, 3, 6, 13, 20, and 27 of the experimental protocol. Rats were euthanized at 1, 3, 7, 14, and 28 days post-injury (n = 6 rats per time-point) and hindlimbs were processed for histology. Results: Significant changes in locomotor parameters included injured and contralateral limb paw area, max dA/dt (limb deceleration/breaking time), stride time, stance time, force time impulse, and fore/hind symmetry, and injured limb maximum force. The most significant and consistent histologic finding was a pathologic fibrotic adhesive lesion at the muscle and tendon interface along the proximal aspect of the patella just distal to the injury site. This lesion was composed of reactive fibroblasts, disorganized collagen fibers, vascular profiles, and a myxomatous ground substance stroma. Conclusions: This work is the first to characterize the clinical and pathologic development of a chronic model of rectus femoris MTJ injury, which resulted in altered mobility likely caused by a strain-induced fibrotic scar along the anterior patella. Notably, both the functional and pathologic changes recapitulated the course of injury progression similar to what is described in humans. This work provides a unique model to study MTJ injury mechanisms for the identification of enhanced treatment options for patients who suffer from activity-related muscle conditions.

Temperature-dependent transport in suspended graphene.

The resistivity of ultraclean suspended graphene is strongly temperature (T) dependent for 50.5 x 10(11) cm(-2), the resistivity increases with increasing T and is linear above 50 K, suggesting carrier scattering from acoustic phonons. At T=240 K the mobility is approximately 120,000 cm2/V s, higher than in any known semiconductor. At the charge neutral point we observe a nonuniversal conductivity that decreases with decreasing T, consistent with a density inhomogeneity <10(8) cm(-2).

Rediscovery of insulin pump treatment of childhood type 1 diabetes.

Currently, goals for the treatment of children and adolescents with type 1 diabetes mellitus are to achieve near normal glycemia; minimize the risks of severe hypoglycemia and excessive weight gain; optimize psychosocial functioning and quality of life (for children and their families); and prevent or delay long-term microvascular complications. Continuous subcutaneous insulin infusion (CSII), or insulin pump therapy, provides a treatment option that can assist in the attainment of all of these goals in all ages of children. Insulin pump therapy provides the opportunity for greater flexibility in meal timing and content due to the convenience of its bolus delivery of insulin. Insulin pump therapy can potentially reduce the risk of exercise-related and nocturnal hypoglycemia, through the use of programmable variable basal infusion rates. In pediatric patients, usage of CSII has been demonstrated to reduce both glycosylated hemoglobin levels and frequency of severe hypoglycemia, without sacrifices in safety, quality of life, or weight gain, particularly in conjunction with the use of new insulin analogs and improvements in pump technology. Clinical studies of safety and efficacy of CSII in children and the use of continuous glucose monitoring to optimize insulin pump therapy are reviewed.

Maternal factors, birthweight, and racial differences in infant mortality: a Georgia population-based study.

Black infant mortality rates (IMRs) are approximately twice those of whites in Georgia and nationwide. This study evaluates maternal factors, particularly marital status, that influence racial differences in infant mortality. Population-based data on 565,730 live births and 7269 infant deaths in Georgia from 1980 to 1985 were examined. The IMR ratio for unmarried compared to married mothers was calculated and adjusted singly for maternal education, age and race, and infant birthweight. In addition, racial differences in IMR were estimated using stratified analysis on the basis of four factors: infant birthweight, maternal age, marital status, and education. When only normal birthweight infants were considered, the IMR, adjusted for maternal education level, was highest for infants born to unmarried black teens (9.5/1000 live births), followed by that for infants born to married black teens (9.1), unmarried black adults (7.5), married black adults (4.8), married white teens (4.4), married white adults (3.4), unmarried white adults (2.4), and unmarried white teens (1.3). When only low birthweight infants were considered, the highest IMR per 1000 was found in infants born to married black adults (119), followed by unmarried black adults (103), married black teens (99.9), unmarried black teens (92.5), married white adults (92.1), married white teens (79.0), unmarried white adults (38.0), and unmarried white teens (26.3). These differences led to a black-to-white IMR risk ratio from 1.3 for low birthweight infants born to unmarried teen or adult mothers to 3.7 for normal birthweight infants born to unmarried teen mothers.(ABSTRACT TRUNCATED AT 250 WORDS)

Sexual practices in the transmission of hepatitis B virus and prevalence of hepatitis delta virus infection in female prostitutes in the United States.

OBJECTIVE: To evaluate heterosexual transmission of hepatitis B virus (HBV) and the prevalence of hepatitis delta virus (HDV) infection in female prostitutes. DESIGN: Survey. SETTING: Sexually transmitted disease clinics, drug treatment programs, detention centers, and/or outreach efforts in eight areas in the United States. PARTICIPANTS: A total of 1368 female prostitutes 18 years of age or older. OUTCOME MEASURES: Seropositivity for HBV and HDV infection. RESULTS: The overall prevalence of past or present HBV infection was 56%: 74% in women who were injecting-drug users (IDUs), 38% in women reporting no history of injecting-drug use (non-IDUs), 51% in whites, 55% in blacks, and 67% in Hispanics. Of 21 HBV carrier IDUs, 21% had HDV infection; of 18 HBV carrier non-IDUs, 6% had HDV infection. In non-IDUs (49%), risk factors for HBV infection were a history of having penile-anal intercourse (odds ratio [OR], 3.1; 95% confidence limits [CL], 1.3, 7.3) and seropositivity for syphilis and human immunodeficiency virus (HIV) infection. In IDUs, factors associated with an increased risk of infection, in addition to behaviors related to injecting-drug use, were the number of lifetime sexual partners, having sexual partners from groups at high risk for HBV infection, and seropositivity for syphilis and HIV infection; spermicide and/or diaphragm use was associated with a markedly decreased risk of HBV infection among blacks (OR, 0.1; 95% CL, 0.03, 0.4) and Hispanics (OR, 0.2; 95% CL, 0.06, 0.9). CONCLUSION: This is the first study to suggest that having anal intercourse and failing to use vaginal contraceptives may facilitate transmission of HBV to women. Our data support guidelines that recommend hepatitis B vaccination for prostitutes and persons with a history of sexually transmitted diseases or multiple sexual partners.

Unexplained febrile illnesses after exposure to ticks. Infection with an Ehrlichia?

The Ehrlichia are tick-borne rickettsial organisms that cause disease in animals throughout the world but that have been previously recognized as human pathogens only in Asia. We have identified six patients with serological evidence of recent infection with an Ehrlichia: a fourfold or greater rise or fall in titer to Ehrlichia canis. All of the patients reported recent tick bites. Rigors, myalgia, headache, nausea, and anorexia were each reported by five patients. Fever was present in all patients and was accompanied by relative bradycardia and leukopenia in five patients, thrombocytopenia and abnormal liver function test results in four, and anemia in three. Five of the six patients were treated with tetracycline hydrochloride, and all recovered. Infection with Ehrlichia should be considered in patients with unexplained febrile illnesses after tick exposure.