Proglycogen and macroglycogen: artifacts of glycogen extraction?

Most recent studies on the physiology of proglycogen and macroglycogen in skeletal muscles have adopted a homogenization-free acid extraction protocol to separate these 2 pools of glycogen. The purposes of this study were to determine (a) whether this protocol is suitable; (b) if the acid-insoluble glycogen fraction corresponds to proglycogen; and (c) if this fraction accounts for most of the changes in muscle glycogen content, irrespective of muscle fiber types. Using the rat as our experimental model, this study shows that when the conditions of acid extraction are optimized, 52% to 64% of glycogen in rat muscles is found as acid-soluble glycogen as opposed to approximately 16% when glycogen is extracted using a homogenization-free extraction protocol. Moreover, there is no evidence that the acid-insoluble glycogen corresponds to proglycogen because gel chromatography of the acid-insoluble and acid-soluble glycogen fractions shows similar elution profiles of high-molecular weight glycogen. Finally, irrespective of muscle fiber types, the acid-soluble glycogen accounts for most of the changes in total muscle glycogen levels during the fasting-to-fed transition, whereas the levels of the acid-insoluble glycogen remain stable or increase marginally. In conclusion, this study shows that the homogenization-free acid extraction of muscle glycogen underestimates the proportion of acid-soluble glycogen and that the findings of the studies that have adopted such an extraction protocol to examine the physiology of acid-insoluble and acid-soluble glycogens require reexamination.     

Diet and lifestyle habits: Association with cardiovascular disease indices in a Nigerian sub-population

Background

There is inadequate evidence regarding the pattern of unhealthy lifestyle behaviours in Nigeria hence the aim of this study was to assess the pattern of lifestyle-related habits that predispose to risk of cardiovascular disease (CVD) indices in a Nigerian population.

Genetic polymorphisms in the tumour necrosis factor locus in childhood acute lymphoblastic leukaemia

Genetic polymorphisms in the tumour necrosis factor (TNF) locus influence the outcome of non-Hodgkin's lymphoma (NHL). We investigated whether these polymorphisms might contribute to the clinical course of childhood acute lymphoblastic leukaemia (ALL). Genomic DNA from 214 childhood ALL patients was analysed. Patients with a high-risk haplotype were older than patients with low-risk haplotype (P = 0.024). No statistically significant associations were found between TNF haplotype and sex, WBC counts, central nervous system involvement, immunophenotype, response to chemotherapy, and event-free survival. These data suggest that genetic polymorphisms in the TNF locus have a limited effect on the outcome of childhood ALL.     

Effectiveness of aggressive management of dyslipidemia in a collaborative-care practice model

The Cardiovascular Risk Identification and Treatment Center was established in 1997, adopting a collaborative-care clinic model for the purpose of improving the management of high-risk patients with dyslipidemia. This was a retrospective analysis of 417 high-risk patients with ≥1 year of follow-up laboratory data. Analysis included changes in total cholesterol, low-density lipoprotein (LDL), high-density lipoprotein (HDL), non-HDL, triglycerides, and total cholesterol to HDL ratio; lipoprotein goal achievement; Framingham risk score; liver function; and cardiovascular events. At baseline, 66% of patients had coronary heart disease (CHD) or equivalent risk, 45% were not receiving dyslipidemia therapy, and 29% were on statin monotherapy. After 3 years in the program, 56% were receiving combination therapy, 41% were on monotherapy, and 2% were not on therapy. The 3 most common treatment regimens were statin plus niacin (36%), statin alone (22%), and niacin alone (14%). All lipoproteins improved from baseline (p <0.001). Overall, 62% to 74% of patients reached singular lipid goals and 35% achieved combined lipid goals. Patients with Framingham 10-year CHD risk of >20% were reduced from 6% to <1%. Only 29 patients (7.0%) had a cardiovascular event, including 5 (1.0%) who experienced a myocardial infarction. Aspartate aminotransferase/alanine transferase elevation >3 times normal occurred in 1% of patients. In conclusion, a collaborative-care practice model adopting individualized, aggressive pharmacologic and nonpharmacologic treatment strategies is highly effective in achieving lipid goals, is sustainable, and is safe. Furthermore, this approach yields reduced projected 10-year CHD risk. A low rate of cardiovascular events was observed.     

Glucose kinetics in rats infused with endotoxin-induced monokines or tumor necrosis factor

This study was conducted to determine if macrophage elaborated monokines in general, and human recombinant tumor necrosis factor (hrTNF alpha) in particular alter glucose metabolism in a manner analogous to that observed in endotoxin-treated animals. Endotoxin-tolerant rats were infused for 3 hr with saline, E. coli endotoxin (100 micrograms/l weight) or monokines contained in conditioned media from endotoxin-stimulated RAW 264.7 cells (1 microgram/ml). Compared to saline- and endotoxin-infused rats, animals receiving the monokine mixture had no change in mean arterial blood pressure or heart rate but exhibited overt signs of morbidity including stupor and diarrhea. Monokine-infused rats remained euglycemic but had elevated lactate concentrations and a 15-30% increase in glucose rate of appearance (Ra). Nontolerant rats received a 3 hr infusion of saline, hrTNF alpha (15 micrograms/100 g), or heat-treated hrTNF alpha. HrTNF alpha infusion increased glucose Ra about 25% compared to the two control groups but did so without producing signs of morbidity seen in the monokine infused animals. Serum TNF levels were 6-fold higher in rats infused with the monokine mixture compared to animals infused with hrTNF alpha, and this reflected the different levels of TNF contained in the monokine mixture and hrTNF alpha infusates. Plasma insulin, glucagon, and catecholamine concentrations were increased in rats infused with either the monokine mixture or hrTNF alpha, but the increases were more pronounced in rats receiving the monokine mixture. The results demonstrate that monokines and hrTNF alpha increase glucose production in vivo, and that the effect may be mediated by endocrine changes known to influence glucose homeostasis.     

Pelvic organ prolapse and the lower urinary tract: The relationship of vaginal prolapse to stress urinary incontinence

Vaginal prolapse and urinary incontinence frequently coexist. Rather than having a cause-and-effect relationship, these two common problems share etiologic factors. Specific tissue and functional deficiencies resulting in prolapse also are significant contributors to lower urinary tract symptoms, particularly stress urinary incontinence. This article reviews this relationship, the etiologic factors, and aspects of the clinical evaluation of the patient with prolapse and stress urinary incontinence.     

Perspectives on "chronic Lyme disease"

There is much controversy about the treatment of Lyme disease with respect to 2 poorly defined entities: “chronic Lyme disease” and “posttreatment Lyme disease syndrome.” In the absence of direct evidence that these conditions are the result of a persistent infection, some mistakenly advocate extended antibiotic therapy (≥6 months), which can do great harm and has resulted in at least 1 death. The purpose of this brief report is to review what is known from clinical research about these conditions to assist both practicing physicians and lawmakers in making sound and safe decisions with respect to treatment.     

Neuroplasticity in Corticolimbic Brain Regions in Patients After Anterior Cruciate Ligament Reconstruction

ContextFear has been cited as the primary barrier to return to sport (RTS) by athletes after anterior cruciate ligament reconstruction (ACLR). Understanding the neural factors that contribute to fear after ACLR may help us to identify interventions for this population.ObjectiveTo characterize the underlying neural substrate of injury-related fear in patients after ACLR versus healthy matched control individuals during a picture imagination task (PIT) consisting of sport-specific images and images of activities of daily living (ADL).DesignCase-control study.SettingResearch laboratory.Patients or Other ParticipantsA total of 24 right-hand–dominant participants (12 with left-sided ACLR and 12 control individuals) were enrolled. Participants underwent full-brain functional magnetic resonance imaging.Main Outcome Measure(s)Functional data were acquired using blood oxygen level–dependent (BOLD) echoplanar imaging. Independent t tests were conducted to identify between-groups differences in BOLD signal changes during all images of the PIT. Paired t tests were computed to examine differences in BOLD signal change between sport-specific and ADL images in the ACLR group.ResultsIncreased activation in the inferior parietal lobule and the mediodorsal thalamus was observed during PIT in the ACLR group. An inability to suppress the default mode network in the ACLR group was noted. The ACLR group exhibited increased activation in the cerebellum and inferior occipital regions during the sport-specific images versus the ADL images, but no other regions of interest demonstrated differences.ConclusionAfter ACLR, patients may be more predisposed to fear, anxiety, and pain during sport-specific activities and ADLs. Psychosocial interventions may be warranted after ACLR to reduce injury-related fear and mitigate potentially maladaptive neuroplasticity.