Cardiomyoplasty: hemodynamic benefit to normal and depressed canine left ventricular function

This study examined the effects of cardiomyoplasty with vascular delay on canine normal and depressed left ventricular (LV) function. To improve viability of the latissimus dorsi muscle (LDM), vascular delay was performed 2 weeks before cardiomyoplasty in 10 mongrel dogs. Two weeks after cardiomyoplasty, LV function was evaluated by simultaneously measuring LV and aortic pressure, and aortic flow. The LDM was stimulated at a ratio of 1:4-1:7 synchronously with ventricular systole. Microspheres (90 mu) were sequentially injected into the left coronary artery to depress LV function. Data were acquired and analyzed on a beat to beat basis. Results were as follows: LDM stimulation significantly augmented LV systolic pressure (LVSP) from 138 +/- 2 to 161 +/- 2* mmHg, the peak rate of change of LV pressure (+dP/dt) from 1888 +/- 46 to 2584 +/- 43* mmHg/sec, aortic systolic pressure (AoSP) from 140 +/- 2 to 159 +/- 2* mmHg, stroke volume (SV) from 11.2 +/- 0.3 to 13.3 +/- 0.3* ml, stroke work (SW) from 19 +/- 1 to 26 +/- 1* gm.m, peak aortic flow (P Qa) from 5542 +/- 142 to 7190 +/- 161* ml/min, and decreased -dP/dt from -1683 +/- 31 to -1689 +/- 49* mmHg/sec (* = p < 0.05). Microsphere injections depressed LV function, but did not affect the magnitude of the net changes between stimulated and nonstimulated beats. However, the percent changes significantly increased. Preconditioning of LDM with vascular delay augments cardiac function in LDM assisted beats. This improved performance was present in both normal as well as depressed LV function groups. Thus, investigations of cardiomyoplasty may not necessarily require a model of severe myocardial dysfunction. Vascular delay offers an important preconditioning method of LDM to augment cardiac function in cardiomyoplasty.     

Effects of sympathetic inhibition on receptive, proceptive, and rejection behaviors in the female rat

The present investigation was designed to examine the effects of sympathetic nervous system (SNS) inhibition on sexual behavior in ovariectomized, steroid-treated female rats. Clonidine, an alpha2-adrenergic agonist, guanethidine, a postganglionic noradrenergic blocker, and naphazoline, an alpha2-adrenoreceptor agonist were used to inhibit SNS activity. Intraperitoneal injections of either 33 micrograms/ml or 66 micrograms/ml clonidine significantly decreased receptive (lordosis) and proceptive (ear wiggles) behaviors and significantly increased rejection behaviors (vocalization, kicking, boxing). Either 25 mg/ml or 50 mg/ml guanethidine significantly decreased receptive and proceptive behavior and had no significant effect on rejection behaviors. Naphazoline significantly inhibited lordosis behavior at either 5 mg/ml or 10 mg/ml doses, significantly inhibited proceptive behavior at 5 mg/ml, and had no significant effect on rejection behaviors. These findings support the hypothesis that SNS inhibition decreases sexual activity in the female rat.     

Absence of myofibrillar creatine kinase and diaphragm isometric function during repetitive activation

Creatine kinase (CK) provides ATP buffering in skeletal muscle and is expressed as 1) cytosolic myofibrillar CK (M-CK) and 2) sarcomeric mitochondrial CK (ScCKmit) isoforms that differ in their subcellular localization. We compared the isometric contractile and fatigue properties of 1) control CK-sufficient (Ctl), 2) M-CK-deficient (M-CK[-/-]), and 3) combined M-CK/ScCKmit-deficient null mutant (CK[-/-]) diaphragm (Dia) to determine the effect of the absence of M-CK activity on Dia performance in vitro. Baseline contractile properties were comparable across groups except for specific force, which was approximately 16% lower in CK[-/-] Dia compared with M-CK[-/-] and Ctl Dia. During repetitive activation (40 Hz, (1)/(3) duty cycle), force declined in all three groups. This decline was significantly greater in CK[-/-] Dia compared with Ctl and M-CK[-/-] Dia. The pattern of force decline did not differ between M-CK[-/-] and Ctl Dia. We conclude that Dia isometric muscle function is not absolutely dependent on the presence of M-CK, whereas the complete absence of CK acutely impairs isometric force generation during repetitive activation.     

Mental status and fragile X expression in relation to FMR-1 gene mutation

The fragile X mental retardation syndrome is caused by unstable expansion of a CGG repeat in the FMR-1 gene. Clinical expression is associated with a large expansion of the CGG repeat. The mutation in the FMR-1 gene and the cytogenetic expression of the fragile site at Xq27.3 have been studied in 52 fragile X male patients. The percentage of the cytogenetic expression of the fragile site at Xq27.3 positively correlates with the mean size of the full mutation in the FMR-1 gene (p < 0.0001) irrespective of the presence of additional premutation alleles. We noted a less frequent occurrence of additional premutation alleles in adult patients compared with juveniles, suggesting a continued mitotic instability in life. Additionally, the level of mental retardation has been ascertained in 35 patients using the Stanford-Binet or Terman-Merrill test of general intelligence. The presence of a full mutation in the FMR-1 gene seemed decisive for the occurrence of mental impairment in the patient. No correlation is observed between the degree of mental retardation and the size of the full mutation. The degree of mental retardation seemed not to be influenced by the presence of premutation alleles in part of the cells in addition to a full mutation. One patient is described with the 'Prader-Willi-like' subphenotype of the fragile X syndrome, showing a deletion in the FMR-1 gene in a part of his cells in addition to a full mutation.