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Biomedical subjects

J Carlson

Publications and source records attributed to J Carlson.

At least 73 records · Page 4Linked to original sources
PubMed2000

Comparison of single- and dual-rod techniques for posterior spinal instrumentation in the treatment of adolescent idiopathic scoliosis.

STUDY DESIGN: Two groups of patients undergoing posterior spinal instrumentation and arthrodesis for treatment of adolescent idiopathic scoliosis were reviewed retrospectively. OBJECTIVE: To compare intraoperative concerns (operative time and blood loss), complications, and outcome in patients undergoing single or double posterior rod instrumentation for treatment of adolescent idiopathic scoliosis. SUMMARY OF BACKGROUND DATA: The current treatment of idiopathic scoliosis includes posterior spinal instrumentation and arthrodesis. The standard configuration is a rectangular construct of dual rods connected by cross-links. Use of a single rod with multiple fixation points has been proposed as an alternative method to decrease operative time and blood loss, and to avoid late deep infections. METHODS: In this study, 21 patients underwent posterior instrumentation using a standard dual-rod construct, and 25 patients underwent posterior instrumentation using a solitary rod with multiple fixation points. Patients were assessed after a minimum 2-year follow-up period. RESULTS: No significant differences were found in blood loss, operative time, or overall frequency of long-term complications. Although not statistically significant, the trend was toward implant prominence in the double-rod group and implant failure in the single-rod group. Implant failure occurred only in instrumentations extending into the lumbar spine. There was no statistical difference in curve progression. CONCLUSIONS: Single-rod instrumentation and dual-rod constructs offered similar curve correction, blood loss, and operative time. However, single-rod instrumentation may be more prone to implant failure when extended into the lumbar spine.

Adolescent↗
PubMed2000

Correlation of intellectual impairment in Parkinson's disease with FDG PET scan.

This study investigated the relationship between regional glucose metabolism with intellectual impairment in patients with Parkinson's disease using statistical parametric mapping. Regional cerebral glucose metabolism using [18F]deoxyglucose (FDG) PET scans were performed on 10 patients with Parkinson's disease. We used the intellectual impairment score from the UPDRS. PET scans were analyzed with SPM96. Patients showed significant positive correlations with left limbic structures such as the cingulate gyrus, parahippocampal gyrus, and medial frontal gyrus. Patients showed significant negative correlations with associative neocortical posterior structures such as bilateral parietal and occipital gyrus. There were significant relationships between regional glucose metabolism and intellectual impairment.

Aged↗
PubMed2000

Search for scalar top and scalar bottom quarks in pp collisions at square root s=1.8 TeV.

We have searched for direct pair production of scalar top and scalar bottom quarks in 88 pb-1 of pp collisions at sqrt[s]=1.8 TeV with the CDF detector. We looked for events with a pair of heavy flavor jets and missing energy, consistent with scalar top (bottom) quark decays to a charm (bottom) quark and a neutralino. The numbers of events that pass our selections show no significant deviation from standard model expectations. We compare our results to the next-to-leading order scalar quark production cross sections to exclude regions in scalar quark-neutralino mass parameter space.

Journal Article↗
PubMed2000

Quick sex determination of mouse fetuses.

We designed a rapid, simple and accurate PCR method to determine sexual identity of mouse fetuses collected on embryonic day 15. A multiplex PCR amplification was used to detect male-specific sequence (Sry) in DNA extracted from fetal livers through SDS denaturation followed by high salt extraction and precipitation. This extraction method resulted in sufficiently purified DNA in < 1 h and was suitable for PCR. The DNA obtained was amplified using a robot thermal cycler for 33 cycles. The reaction was performed in 50 microl, using two sets of primers specific for Sry gene (chromosome Y) and IL3 gene (chromosome 11). Amplification duration was 1.5 h. The assessment of the results was done by electrophoresis in 3% agarose run at high voltage. The 402 bp band (Sry) obtained identifies the male fetuses and the 544 bp product (IL3) confirms the correct amplification of the template DNA. The entire procedure took < 4 h. The specificity of the method was confirmed by fluorescent in situ hybridization using a specific male probe on cultured male and female neural stem cells. This method allowed the preparation and culture of pure male and female neural stem cells from fetal tissue.

Animals↗
PubMed2000

Petrochemical exposure and menstrual disturbances.

BACKGROUND: An exploratory, cross-sectional retrospective study was conducted to examine the effects of benzene exposure on menstrual problems. METHODS: The study was based on a survey administered to over 3,000 women who worked in a large petrochemical company in Beijing, China. An abnormal menstrual cycle length (AMCL), defined as an average menstrual cycle length of greater than 35 days or less than 21 days, is the major outcome of interest. RESULTS: After 7 years of benzene exposure, the adjusted odds ratio of having AMCL for each additional 5 years of exposure was 1.71 (95% CI 1.27-2.31). Feeling stressed at work was also an important predictor. CONCLUSIONS: This study suggests a significant association of benzene exposure and perceived stress with menstrual disturbance. A prospective study is needed to confirm this finding.

Adult↗
PubMed2000

Selective neurotoxic effects of nicotine on axons in fasciculus retroflexus further support evidence that this a weak link in brain across multiple drugs of abuse.

When administered continuously for several days at relatively low plasma levels, a variety of drugs of abuse with strong dopaminergic actions induce degeneration in axons traveling from the lateral habenula through the sheath of fasciculus retroflexus to midbrain monoaminergic nuclei. With some of these drugs, such as cocaine, this is virtually the only degeneration induced in brain. Nicotine given continuously also selectively induces degeneration in fasciculus retroflexus, but in the other half of the tract: the cholinergic axons running from medial habenula in the core of the tract to the interpeduncular nucleus. Fasciculus retroflexus appears to be a weak link in brain for diverse drugs of abuse when administered incessantly for several days. Alterations in this tract would be predicted to be especially important for the genesis of the symptomatology which develops during drug binges, residual effects of such binges, and the processes underlying relapse.

Amphetamines↗
PubMed2000

Clinical economics: calculating the cost of acute postoperative pain medication.

Few data are available that address the cost of postoperative pain management, although such knowledge would enhance our understanding of caregiver choices related to direct medical costs, such as type, frequency, and route of medication. This article describes the cost of postoperative pain medications before and after an educational program provided to nurses, pharmacists, and physicians in six community hospitals. Medication costs were calculated by averaging across all brands the average wholesale price of the most common dose administered in the sample for each medication. The median cost of postoperative pain medication across all days, all surgeries, was $9.46. Calculating the cost of acute postoperative pain medication suggested that cost over stay is highly influenced by the use of a few expensive medications. The relationship of medication cost to length of stay (LOS), function, and pain intensity is discussed.

Acute Disease↗
PubMed2000

Does ultrasound influence experimentally induced thrombus formation in the central artery of the rabbit ear?

BACKGROUND: Thrombosis is one of the most important causes of morbidity in the medical field. Several independent in vitro studies have shown that the fibrinolytic process may be enhanced by ultrasound, but the effect of ultrasound on thrombus formation in vivo is unexplored. The present study was designed to investigate this matter. METHODS: In a blind randomized study, standardized arteriotomies and intimectomies were performed on the central arteries of the ears of 25 rabbits. The rabbits were allocated to two groups, an untreated control group and a group treated with ultrasound (10 pulses of frequency 1 MHz and intensity 1 W/cm(2) per millisecond giving an averaged intensity of 0.01 W/cm(2)). Immediately after reperfusion, patency was confirmed by a manual empty/refill test, after which blood-flow was monitored using ultrasonic flow-probes twice a minute for two hours. At two hours, patency was rechecked. RESULTS: All vessels were patent at reperfusion, but only seven vessels (three control, four treated) were patent when flow-rate measurements started. At 2 h, patency-frequencies were 12/23 in the control group and 11/22 in the treated group. Flow-rate curves in patent vessels in both groups were similar. Microscopic investigation at one week showed no difference in thrombus accumulation. CONCLUSIONS: Ultrasound with the above characteristics does not significantly improve patency in vivo.

Animals↗
PubMed2000

Detection of inter-atrial conduction defects with unfiltered signal-averaged P-wave ECG in patients with lone atrial fibrillation.

AIMS: To demonstrate a possible inter-atrial conduction delay in patients with lone paroxysmal atrial fibrillation (PAF) using 'unfiltered' signal-averaged P-wave ECG (PSAECG) and compare these results with those obtained with conventional filter settings. METHODS AND RESULTS: Twenty one patients with lone PAF and 20 healthy volunteers (control group) were enrolled in the study. An orthogonal lead surface ECG was high-pass filtered at 0.8 Hz, averaged with template matching, and combined into a spatial magnitude ('unfiltered' technique). Results were compared with conventionally filtered (40-300 Hz) PSAECG. The filtered technique revealed no differences in P-wave duration between the two groups (121 +/- 12 vs 128 +/- 15 ms, control and PAF groups respectively, ns). Double-peaked P-wave spatial magnitudes (interpeak distance >30 ms) were revealed in 11 of 21 PAF patients but only in two of 18 controls (P<0.01). The nadir in the spatial magnitude was located significantly later in the PAF group (114 +/- 13 vs 103 +/- 9 ms, P<0.01). CONCLUSION: 'Unfiltered' PSAECG revealed significant differences in orthogonal P-wave morphology in patients with lone PAF, indicating the possibility of an inter-atrial conduction delay, while conventional P-wave duration analysis failed to discriminate between the two groups.

Adult↗
PubMed2000

Cheek cell phospholipids in human infants: a marker of docosahexaenoic and arachidonic acids in the diet, plasma, and red blood cells.

BACKGROUND: Assessment of essential fatty acid status requires collection of blood or adipose tissue samples. However, these invasive techniques cannot always be used in studies involving infants, young children, or subjects from whom it is difficult to obtain blood. A body tissue that is easy to access is the buccal mucosa (cheek cells). OBJECTIVE: The objective was to investigate the degree to which fatty acids of cheek cells reflect the fatty acid content of plasma, red blood cells, and the diet. DESIGN: Thirty-one infants aged 12 mo were enrolled. Five infants were fed human milk and 26 infants received formulas that provided a wide range of arachidonic acid and docosahexaenoic acid (DHA) intakes. Cheek cells were collected on a small piece of gauze by gently swabbing the inside of the cheek 3 times. Lipids were extracted from the gauze and the phospholipid fatty acid content of the cheek cells was determined. RESULTS: Cheek cell DHA and arachidonic acid in phospholipids were significantly correlated with DHA and arachidonic acid in plasma [r = 0.61 (P < 0.001) and r = 0.37 (P <0.05), respectively], red blood cells [r = 0.58 (P < 0.001) and r = 0.37 (P < 0.05), respectively], and the diet [r = 0.65 (P < 0.001) and r = 0. 51 (P < 0.01), respectively]. CONCLUSIONS: Given these correlations and the ease and noninvasive nature of this technique, cheek cell fatty acids may serve as a marker of the essential fatty acid content, especially of DHA and arachidonic acid, in plasma, red blood cells, and the diet.

Analysis of Variance↗
PubMed2000

Blood group A antigen is a coreceptor in Plasmodium falciparum rosetting.

The malaria parasite Plasmodium falciparum utilizes molecules present on the surface of uninfected red blood cells (RBC) for rosette formation, and a dependency on ABO antigens has been previously shown. In this study, the antirosetting effect of immune sera was related to the blood group of the infected human host. Sera from malaria-immune blood group A (or B) individuals were less prone to disrupt rosettes from clinical isolates of blood group A (or B) patients than to disrupt rosettes from isolates of blood group O patients. All fresh clinical isolates and laboratory strains exhibited distinct ABO blood group preferences, indicating that utilization of blood group antigens is a general feature of P. falciparum rosetting. Soluble A antigen strongly inhibited rosette formation when the parasite was cultivated in A RBC, while inhibition by glycosaminoglycans decreased. Furthermore, a soluble A antigen conjugate bound to the cell surface of parasitized RBC. Selective enzymatic digestion of blood group A antigen from the uninfected RBC surfaces totally abolished the preference of the parasite to form rosettes with these RBC, but rosettes could still form. Altogether, present data suggest an important role for A and B antigens as coreceptors in P. falciparum rosetting.

ABO Blood-Group System↗
PubMed2000

Increased vasoconstrictor sensitivity in obstructive sleep apnea.

We studied vasoconstrictor sensitivity and cholinergic responsiveness of the forearm vasculature in 10 male patients with obstructive sleep apnea (OSA) and 10 healthy controls. Subjects with regular medication, known arterial hypertension, diabetes mellitus, or dyslipidemia were not included in this study. Age, body mass index, blood pressure, blood glucose, serum lipids, and baseline forearm vascular conductance (derived from venous occlusion plethysmography and intra-arterial blood pressure measurement) did not differ significantly between these two groups. With use of three dosage steps each, angiotensin II and acetylcholine were successively infused into the brachial artery. During infusion of angiotensin II, mean conductance was 39.6% lower (P = 0.002) in the OSA patients compared with that in the control subjects. Vascular responsiveness to increasing dosages of acetylcholine was not significantly altered in the OSA group. These findings suggest an enhanced vasoconstrictor sensitivity in the forearm vasculature in OSA. The hypothesis that endothelial function in OSA is impaired independently of other cardiovascular risk factors is not supported by the present results.

Acetylcholine↗
PubMed2000

Densovirinae as gene transfer vehicles.

Densoviruses present an attractive opportunity to develop expression vectors for insects. They exhibit several features that are beneficial for such vectors. The genomes of densoviruses are among the smallest of animal DNA viruses, and, therefore are easier to use for cloning and transfection procedures. The fact that cloned densovirus genomes are infectious greatly simplifies their applications. It seems that both densovirus promoters have high constitutive activity and they can be further transactivated with NS. The major nonstructural protein, NS1, can retain its functions even if fused to a foreign protein. If the recombinant genome carrying a gene of interest is supplied with the missing virus functions, it can be packaged into transducing particles. The packaging capacity of the densovirus particles can accommodate a foreign gene encoding a polypeptide of up to 150 kDa. Finally, the functions missing from the recombinant densovirus genome that are necessary for the production of transducing particles can be supplied in several different ways: they can be expressed from a helper plasmid, in cells transformed with the virus genes, or from an RNA virus. The last two methods produce transducing particles which are free of wild type virus. Densovirus transducing particles can be used for the delivery and expression of a gene of interest in insect cell culture or living insects. Transducing particles expressing reporter genes can be valuable tools in the study of viral pathogenesis and perhaps in the genetic manipulation of insects.

Animals↗
PubMed2000

Liver transplantation in a patient at psychosocial risk.

Psychosocial assessment of transplant candidates is a challenging task. Securing adequate information is made more difficult when patients present with fulminant hepatic failure. When the patient cannot be interviewed and the family is reluctant to provide vital information, a comprehensive pretransplant psychosocial evaluation is virtually impossible. However, even the most difficult cases have the potential for a positive result when a good psychosocial profile of the patient is obtained after transplantation, a team treatment plan is developed and carried out which addresses current and anticipated problems, and the patient obtains mental health treatment.

Adult↗
PubMed2000

Physiological issues surrounding the performance of adolescent athletes.

More than ever, many young athletes are being encouraged to train intensely for sporting competitions from an early age. Compared with studies in adults, less is known about the physiological trainability of adolescents. The velocity of physical growth during the adolescent years makes research with a group of young athletes particularly difficult. The purpose of this review is to discuss a number of physiological issues that surround the performances of the adolescent athlete. Research has highlighted the role of growth hormone (GH) in the abrupt acceleration of linear growth that occurs during adolescence. In addition, GH has been shown to be sensitive to exercise following short term intervention studies. The reduced anaerobic power of the adolescent athlete compared with that of an adult athlete has been attributed to the intrinsic properties of the muscle that are yet to be fully understood. Resistance training studies in male adolescents, and to a lesser extent female adolescents, highlight the substantial relative strength gains that can be obtained. Aerobic trainability in young boys appears to improve markedly during the adolescent years. One of the most plausible explanations for this observation is the 'trigger hypothesis' which links increased aerobic improvements in adolescence with hormonal changes and substantial growth of the cardiorespiratory and musculoskeletal systems. Studies of aerobic trainability in adolescent girls are too scarce to be conclusive. An understanding of the impact of long term intensive training on adolescent athletes is difficult to ascertain because physical stresses vary both between and within sports. There is, however, limited evidence to suggest that 'intense' training does not impair normal growth, development or maturation. Adolescent athletes who experience rapid growth as well as large increases in training volumes may be vulnerable to overuse injuries.

Adolescent↗
PubMed1999

[Atrial fibrillation--new knowledge yields new therapeutic possibilities].

Atrial fibrillation (AF) is the most common cardiac arrhythmia prompting treatment. Advances in our knowledge of the pathophysiology of AF provide the basis for new and improved treatment modalities. Thus, focal excitation and localised impulse conduction defects are possible trigger factors which can be counteracted by focal ablation and pacing synchronisation, respectively. Perpetuation of AF, caused by continuous multisite re-entry, is promoted by successive shortening of repolarisation. Internal defibrillation and anatomical limitation of re-entry are treatments that counteract perpetuation of the arrhythmia. Current knowledge of AF and the application of new treatments are discussed by the Lund AF research group.

Atrial Fibrillation↗
PubMed1999

Lymphohematopoietic stem cell engraftment.

Traditional dogma has stated that space needs to be opened by cytoxic myeloablative therapy in order for marrow stem cells to engraft. Recent work in murine transplant models, however, indicates that engraftment is determined by the ratio of donor to host stem cells, i.e., stem cell competition. One hundred centigray whole body irradiation is stem cell toxic and nonmyelotoxic, thus allowing for higher donor chimerism in a murine syngeneic transplant setting. This nontoxic stem cell transplantation can be applied to allogeneic transplant with the addition of a tolerizing step; in this case presensitization with donor spleen cells and administration of CD40 ligand antibody to block costimulation. The stem cells that engraft in the nonmyeloablated are in G0, but are rapidly induced (by 12 hours) to enter the S phase after in vivo engraftment. Exposure of murine marrow to cytokines (IL-3, IL-6, IL-11 and steel factor) expands progenitor clones, induces stem cells into cell cycle, and causes a fluctuating engraftment phenotype tied to phase of cell cycle. These data indicate that the concepts of stem cell competition and fluctuation of stem cell phenotype with cell cycle transit should underlie any new stem cell engraftment strategy.

Animals↗