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Biomedical subjects

J Jarvis

Publications and source records attributed to J Jarvis.

At least 19 recordsLinked to original sources
PubMed2005

Implantable device for long-term electrical stimulation of denervated muscles in rabbits.

Although denervating injuries produce severe atrophic changes in mammalian skeletal muscle, a degree of functional restoration can be achieved through an intensive regime of electrical stimulation. An implantable stimulator was developed so that the long-term effects of different stimulation protocols could be compared in rabbits. The device, which is powered by two lithium thionyl chloride batteries, is small enough to be implanted in the peritoneal cavity. All stimulation parameters can be specified over a wide range, with a high degree of resolution; in addition, up to 16 periods of training (10-180 min) and rest (1-42 h) can be set in advance. The microcontroller-based device is programmed through a bidirectional radiofrequency link. Settings are entered via a user-friendly computer interface and annotated to create an individual study protocol for each animal. The stimulator has been reliable and stable in use. Proven technology and rigorous quality control has enabled 55 units to be implanted to date, for periods of up to 36 weeks, with only two device failures (at 15 and 29 weeks). Changes in the excitability of denervated skeletal muscles could be followed within individual animals. Chronaxie increased from 3.24 +/- 0.54 ms to 15.57 +/- 0.85 ms (n = 55, p < 0.0001) per phase in the 2 weeks following denervation.

Animals↗
PubMed2005

Steroids prevent engraftment syndrome after autologous hematopoietic stem cell transplantation without increasing the risk of infection.

Engraftment syndrome (ES) following autologous hematopoietic stem cell transplantation (AHSCT) is characterized by fever and rash. In January 2002, we instituted steroid prophylaxis for ES from day +4 to +14. This study was conducted to assess whether this practice increased the risk of infection. In total, 194 consecutive patients were reviewed, 111 did not receive steroid prophylaxis (group A), and 83 did (group B). Initial antimicrobial prophylaxis was the same in both groups. There were no significant differences between groups in age, gender, race, prior radiation therapy, number of prior chemotherapy regimens, disease status at transplant, mobilization regimen, days of leukopheresis, CD34(+) cell dose, and days to platelet and neutrophil engraftment. Group B had significantly fewer patients with non-Hodgkin's lymphoma and multiple myeloma, shorter median duration from diagnosis to transplant, lower risk of ES, and shorter mean length of hospital stay. The incidence of early and late microbiologically confirmed infections was not significantly different between groups. Types of infections and types of organisms identified were similar in both groups. Hospital readmission rates were similar in both groups. Steroid prophylaxis significantly decreases the risk of ES following AHSCT, and is associated with shortened hospitalization, without increasing risk of infection.

Adolescent↗
PubMed2005

Diabetes screening anxiety and beliefs.

AIMS: This study assesses the impact of screening for diabetes on anxiety levels in an ethnically mixed population in the UK, and explores whether beliefs about Type 2 diabetes account for these anxiety levels. METHODS: This cross-sectional study recruited individuals who were identified at high risk of developing diabetes through general practitioners' (GPs) lists or through public media recruitment. Participants completed an oral glucose tolerance test (OGTT). Between blood tests, participants completed the Spielberger State Anxiety Scale Short Form, the Emotional Stability Scale of the Big Five Inventory 44 and three scales from the Diabetes Illness Representations Questionnaire, revised for this study. RESULTS: Of the 1339 who completed the OGTT and questionnaire booklet, 54% were female, with 21% from an Asian background. Forty-five per cent of participants reported little to moderate amounts of anxiety at screening (mean 35.2; sd = 11.6). There was no significant effect of family history of diabetes, ethnic group or recruitment method on anxiety. The only variable significantly associated (negatively) with anxiety was the personality trait of emotional stability. Of responders, 64% and 61% agreed that diabetes was caused by diet or hereditary factors, respectively. Only 155 individuals (12%) agreed that diabetes was serious, shortens life and causes complications. CONCLUSIONS: The results of this study replicate that of previous studies, indicating that screening for diabetes does not induce significant anxiety. Bivariate analysis indicated that individuals who perceived diabetes to be serious, life shortening and resulting in complications had higher anxiety scores, the personality trait of emotional stability being the strongest predictor of anxiety.

Adult↗
PubMed2005

Relationship between chemical structure and the occupational asthma hazard of low molecular weight organic compounds.

AIMS: To investigate quantitatively, relationships between chemical structure and reported occupational asthma hazard for low molecular weight (LMW) organic compounds; to develop and validate a model linking asthma hazard with chemical substructure; and to generate mechanistic hypotheses that might explain the relationships. METHODS: A learning dataset used 78 LMW chemical asthmagens reported in the literature before 1995, and 301 control compounds with recognised occupational exposures and hazards other than respiratory sensitisation. The chemical structures of the asthmagens and control compounds were characterised by the presence of chemical substructure fragments. Odds ratios were calculated for these fragments to determine which were associated with a likelihood of being reported as an occupational asthmagen. Logistic regression modelling was used to identify the independent contribution of these substructures. A post-1995 set of 21 asthmagens and 77 controls were selected to externally validate the model. RESULTS: Nitrogen or oxygen containing functional groups such as isocyanate, amine, acid anhydride, and carbonyl were associated with an occupational asthma hazard, particularly when the functional group was present twice or more in the same molecule. A logistic regression model using only statistically significant independent variables for occupational asthma hazard correctly assigned 90% of the model development set. The external validation showed a sensitivity of 86% and specificity of 99%. CONCLUSIONS: Although a wide variety of chemical structures are associated with occupational asthma, bifunctional reactivity is strongly associated with occupational asthma hazard across a range of chemical substructures. This suggests that chemical cross-linking is an important molecular mechanism leading to the development of occupational asthma. The logistic regression model is freely available on the internet and may offer a useful but inexpensive adjunct to the prediction of occupational asthma hazard.

Asthma↗
PubMed2004

Clinical outcomes of patients with impaired left ventricular ejection fraction undergoing autologous bone marrow transplantation: can we safely transplant patients with impaired ejection fraction?

Experience with autologous bone marrow transplantation (ABMT) in patients with impaired left ventricular ejection fraction (LVEF) or heart failure (HF) is limited. We identified 308 consecutive patients who underwent ABMT for Hodgkin's or non-Hodgkin's lymphoma at our institution (1996-2003). Patient characteristics, clinical course and overall survival were compared between patients with preserved ( > or = 50%) or impaired ( < 50%) LVEF. Of the 308 patients identified, 20 had baseline impaired LVEF (four with LVEF < or = 40%, all NYHA class I-II HF). None of the patients with post-ABMT echocardiogram had worsened LVEF (n = 7). Among the 20 patients with impaired LVEF, four patients had reversible cardiac complications post-ABMT (including worsening HF). The two deaths observed in the impaired LVEF group were both due to noncardiac causes. The 5-year survival was similar between patients with preserved and impaired LVEF (P = 0.43). Careful selection of patients with stable, mild-to-moderate HF and impaired LVEF for ABMT can achieve similar long-term survival. As medical care for HF and ABMT improves, the exclusion criteria for ABMT with regard to HF and impaired LVEF should be re-examined.

Adult↗
PubMed2001

Liver resections in Auckland 1998-2001: mortality, morbidity and blood product use.

AIMS: There has been a marked increase in the number of liver resections undertaken at Auckland Hospital since 1998. Low central venous pressure anaesthesia was routinely used for liver resection during this period. The aim of this study was to review this experience, with particular emphasis on the peri-operative outcomes of morbidity, mortality and blood product use. METHODS: All patients undergoing liver resection from January 1998 to May 2001 were included in the review. Standardised data were collated retrospectively from hospital records and transferred to an electronic database for analysis. RESULTS: Of 123 patients undergoing liver resection, 113 were elctive and ten were urgent operations. 65% had major resections and 10% had synchronous extrahepatic surgery. There were three post-operative deaths (mortality 2.4%) due to liver failure and sepsis. One or more complications occurred in 68 patients (morbidity 55%). 72% did not receive a blood transfusion during their hospital stay. Only two of 113 elective patients required a massive blood transfusion (ten or more units). CONCLUSIONS: Mortality in the study period was low but morbidity remains significant. Blood product use was low in elective patients. These results compare well with those of specialised hepatobiliary units internationally.

Adolescent↗
PubMed2000

An analysis of a preoperative pediatric autologous blood donation program.

OBJECTIVE: To determine the efficacy of a pediatric autologous blood donation program. DESIGN: A retrospective study of patient charts and blood-bank records. SETTING: The Children's Hospital of Eastern Ontario, Ottawa, a tertiary care, pediatric centre. PATIENTS: One hundred and seventy-three children who received blood transfusions for a total of 182 procedures between June 1987 and June 1997. INTERVENTIONS: Autologous and homologous blood transfusion required for major surgical intervention, primarily spinal fusion. MAIN OUTCOME MEASURES: Surgeons' accuracy in predicting the number of autologous blood units required for a given procedure, compliance rate (children's ability to donate the requested volume of blood), utilization rate of autologous units and rate of allogeneic transfusion. RESULTS: The surgeons' accuracy in predicting the number of autologous units required for a given procedure was 53.8%. The compliance rate of children to donate the requested amount of blood was 80.3%. In children below the standard age and weight criteria for blood donation the compliance rate was 75.5%. The utilization rate of autologous units obtained was 84.4% and the incidence of allogeneic transfusion was 26.6%. CONCLUSIONS: There was a high rate of compliance and utilization of predonated autologous blood in the children in the study. Preoperative blood donation programs are safe and effective in children, even in those below the standard age and weight criteria of 10 years and 40 kg.

Adolescent↗
PubMed1999

Congenital kyphosis in myelomeningocele. The effect of cordotomy on bladder function.

To determine the effect of cordotomy on the function of the bladder during surgical correction of congenital kyphosis in myelomeningocele, we reviewed 13 patients who had this procedure between 1981 and 1996. The mean age of the patients at operation was 8.9 years (3.7 to 16) and the mean follow-up was 4.8 years (1.3 to 10.8). Bladder function before and after operation was assessed clinically and quantitatively by urodynamics. The mean preoperative kyphosis was 117 degrees (52 to 175) and decreased to 49 degrees (1 to 89) immediately after surgery. At the latest follow-up, a mean correction of 52% had been achieved. Only one patient showed deterioration in bladder function after operation. Eight out of the nine patients who had urodynamic assessment had improvement in bladder capacity and compliance, and five showed an increase in urethral pressure. One patient developed a spastic bladder and required subsequent surgical intervention. Cordotomy, at or below the level of the kyphosis, allows excellent correction of the structural deformity.

Adolescent↗
PubMed1998

The influence of desmopressin on blood loss during spinal fusion surgery in neuromuscular patients.

STUDY DESIGN: A double-blind study comparing the effects of desmopressin and a placebo (normal saline) on blood loss during spinal instrumentation for neuromuscular scoliosis. OBJECTIVE: To determine the effectiveness of desmopressin acetate (DDAVP) in reducing operative blood loss in hemostatically normal patients undergoing spinal fusion surgery for neuromuscular scoliosis. SUMMARY OF BACKGROUND DATA: Desmopressin acetate has been shown to improve bleeding times and to provide surgical hemostasis in patients with platelet disorders. Its effect in reducing bleeding times in normal patients has been the subject of debate in several surgical specialties. Recent observations that DDAVP seems to reduce bleeding times and blood loss in patients undergoing spinal surgery for neuromuscular scoliosis warranted a more focused analysis on its role in this surgical procedure. METHODS: Patients undergoing surgery for neuromuscular scoliosis were randomly assigned to receive DDAVP or placebo. Bleeding times and plasma clotting factors were measured before the administration of the DDAVP or placebo and 60 minutes after. Operative blood loss was carefully measured. RESULTS: Although the administration of DDAVP decreased overall blood loss by an average of 19% compared with blood loss in the placebo group and blood loss per vertebra fused by an average of 15%, these results were not statistically significant. CONCLUSIONS: Bleeding time and blood loss seem to respond better to DDAVP in some patients, in whom significant decreases were observed, than they do in others. The problem is in identifying those patients in whom a decrease in bleeding time will be elicited after administration of DDAVP. Preoperative administration of DDAVP to such patients should significantly decrease operative blood loss.

Adolescent↗
PubMed1997

[Embryology of the human hip].

This description of the prenatal development of the hip joint is based on observations made in 126 spontaneously aborted human embryos and fetuses. Their gestational age varied between 6 weeks and term. Particular attention was paid to structures that can be recognized during the sonographic examination of the hip, be it during pregnancy or at the time of birth. At 6 weeks, the anlage of the hip joint is already visible. By the time the fetal period starts, all components of the hip joint are clearly recognizable. Serial sections allow the histomorphometric determination of the coverage of the femoral head.

Female↗
PubMed1997

Memories of childhood neglect and abuse: corroboration in a series of sisters.

Reports from 87 community-based sister-pairs, selected for high rates of neglect or abuse in childhood, have been used to establish validity of the CECA, a retrospective interview measure of childhood experience. Corroboration was based on independent assessments of sisters' accounts of what happened to each other in childhood. Corroboration of scales assessing parental neglect, physical abuse in the household and sexual abuse (either household or nonhousehold) was satisfactory, with a mean correlation for the three experiences of .60 (weighted kappa [Kw]). Concordance reflected the degree to which experience was shared and was judged by comparing the sisters' accounts of their own experience. Among sisters with shared (concordant) experience for neglect or abuse, corroboration was high (mean of .74), but for those with nonshared (nonconcordant) experience it was largely absent (mean of .01). The degree to which the experiences of neglect or abuse were concordant was related to whether the perpetrator was a member of the household. Neglect and physical abuse were by definition from household members (mainly parents) and involved high concordance of experience. Sexual abuse occurred from many sources and in practice was commonly from an adult living outside the household and such experiences were less likely to be shared by sisters. An overall index indicating the presence of at least one abusive experience before the age of 17 showed a concordance of .64 with corroboration between sisters as high as .70. Issues involving retrospective recall and measurement are discussed.

Adolescent↗
PubMed1995

Increased muscle carnitine palmitoyltransferase II mRNA after increased contractile activity.

The capacity of skeletal muscle to oxidize fatty acids increases with endurance training. The oxidation of long-chain fatty acids occurs in mitochondria and is initiated by a carnitine-dependent transport step in which three enzymes help fatty acyl groups enter the matrix compartment. The purpose of this study was to determine whether pretranslational regulation of one of these three enzymes, carnitine palmitoyltransferase II (CPT II), as estimated from the level of CPT II mRNA, plays a role in the doubling of CPT activity in skeletal muscle of rats subjected to daily 2-h bouts of running on treadmills (P. A. Móle, L. B. Oscai, and J. O. Holloszy. J. Clin. Invest. 50: 2323-2330, 1971). After 100 min/day of running on motor-driven treadmills for 2 wk, CPT II mRNA in the plantaris muscle was unchanged when normalized per unit of extracted RNA but was 50% higher (P < 0.05) over sedentary controls when normalized per unit of muscle wet weight. To test whether additional contractile activity would make CPT II mRNA even higher, continuous indirect electrical stimulation was imposed on the tibialis anterior muscles. After 9 days of chronic stimulation, CPT II mRNA was 63, 221, and 137% greater than control (P < 0.001) when normalized to extracted RNA, muscle wet weight, and whole muscle, respectively, compared with the muscle in the control rats. These data indicate that pretranslational regulation of CPT II occurs in response to increased contractile activity in skeletal muscle.

Animals↗
PubMed1993

Stimulation-induced damage in rabbit fast-twitch skeletal muscles: a quantitative morphological study of the influence of pattern and frequency.

The aim of this study was to determine whether muscle fibre degeneration brought about by chronic low-frequency electrical stimulation was related to the pattern and frequency of stimulation. Rabbit fast-twitch muscles, tibialis anterior and extensor digitorum longus, were stimulated for 9 days with pulse trains ranging in frequency from 1.25 Hz to 10 Hz. Histological data from these muscles were analysed with multivariate statistical techniques. At the lower stimulation frequencies there was a significantly lower incidence of degenerating muscle fibres. Fibres that reacted positively with an antineonatal antibody were most numerous in the sections that revealed the most degeneration. The dependence on frequency was generally similar for the two muscles, but the extensor digitorum longus muscles showed more degeneration than the tibialis anterior at every frequency. Muscles subjected to 10 Hz intermittent stimulation showed significantly less degeneration than muscles stimulated with 5 Hz continuously, although the aggregate number of impulses delivered was the same. The incidence of degeneration in the extensor digitorum longus muscles stimulated at 1.25 Hz was indistinguishable from that in control, unstimulated muscles; for the tibialis anterior muscles, this was also true for stimulation at 2.5 Hz. We conclude that damage is not an inevitable consequence of electrical stimulation. The influence of pattern and frequency on damage should be taken into account when devising neuromuscular stimulation regimes for clinical use.

Animals↗
PubMed1992

Quantitative morphology of stimulation-induced damage in rabbit fast-twitch skeletal muscles.

The purpose of this study was to examine the contention that stimulation-induced damage, resulting in degeneration with subsequent regeneration, plays a major role in the transformation of fibre type brought about by chronic electrical stimulation. Data from histological and histochemical sections of 9-day-stimulated rabbit fast-twitch muscles were analysed with multivariate statistical techniques. Fibre degeneration and regeneration varied non-systematically between sample areas at any given cross-sectional level. In the extensor digitorum longus muscle, but not in the tibialis anterior, there was more degeneration in proximal than in distal portions of the muscle. The extensor digitorum longus muscle consistently showed more degeneration than the tibialis anterior muscle. Degeneration was less extensive for an intermittent pattern of stimulation that delivered half the aggregate number of impulses of continuous stimulation. Degeneration and regeneration varied markedly between individual rabbits in each of the groups. Sections that revealed the most degeneration and regeneration also had more fibres that reacted positively with an anti-neonatal antibody. Rigorous analysis of different sources of variation has helped to explain apparent conflicts in the literature. The incidence of muscle fibre damage in the stimulated tibialis anterior muscle is low, showing that the contribution of degenerative-regenerative phenomena to fibre type conversion in this muscle is insignificant.

Animals↗
PubMed1992

Seat-belt injuries of the spine in young children.

Seat-belt fractures of the lumbar spine in adolescents and adults are well recognised but there are few reports of these injuries in young children. We reviewed all seat-belt injuries in skeletally immature patients (Risser 0), seen at a tertiary referral centre between 1974 and 1991. There were ten cases, eight girls and two boys, with an average age of 7.5 years (3 to 13). Four distinct patterns of injury were observed, most commonly at the L2 to L4 level. Paraplegia, which is thought to be uncommon, occurred in three of our ten cases. Four children had intra-abdominal injuries requiring laparotomy. There was a delay in diagnosis either of the spinal or of the intra-abdominal injury in five cases, although all had contusion of the abdominal wall, the 'seat-belt sign'. Treatment of the fractures was conservative, by bed rest and then hyperextension casts. The incidence of this potentially devastating injury can be reduced by the optimal use of restraints, but there is often a delay in diagnosis. Our classification system may aid in the early detection and evaluation of this injury.

Accidents, Traffic↗
PubMed1992

The fetal acetabulum. A histomorphometric study of acetabular anteversion and femoral head coverage.

To study the development of the acetabulum in the early fetal period, 39 embryologic specimens were reviewed in detail. Histologic serial sections were made through 47 hips in the transverse plane. Measurements of acetabular anteversion and femoral head coverage revealed that both parameters depend on the exact level of sectioning. However, when measured at the level of the maximum diameter of the femoral head, they did not show significant variation through the embryonic and early fetal stages (six to 20 weeks). This is in contradistinction to the late fetal period. The hip does remain covered during this early fetal period. Congenital dislocation of the hip is not an early developmental condition. This accounts for the absence of any reports of hip dislocations in the first half of gestation.

Acetabulum↗