Beam-Target Helicity Asymmetry for γ[over →]n[over →]→π^{-}p in the N^{*} Resonance Region

We report the first beam-target double-polarization asymmetries in the γ+n(p)→π^{-}+p(p) reaction spanning the nucleon resonance region from invariant mass W=1500 to 2300 MeV. Circularly polarized photons and longitudinally polarized deuterons in solid hydrogen deuteride (HD) have been used with the CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Lab. The exclusive final state has been extracted using three very different analyses that show excellent agreement, and these have been used to deduce the E polarization observable for an effective neutron target. These results have been incorporated into new partial wave analyses and have led to significant revisions for several γnN^{*} resonance photocouplings.

Potential involvement of retroviral elements in human dementias

Creutzfeldt-Jakob disease (CJD) is a dementia of humans caused by a class of infectious agents with several biological properties similar to those of conventional viruses. The molecular nature of this group of agents is enigmatic, for neither an agent-specific nucleic acid nor a non-host protein has yet been identified. Recent transmissions of familial CJD dementias to rodents suggest that this class of agent can be integrated into the germline. Furthermore, tissue culture studies indicate that CJD causes transformation of cells in a manner reminiscent of slowly oncogenic retroviruses. Currently characterized retroviral-like elements include many forms that do not have 'typical' retroviral ultrastructural morphology; several forms are also known to be resistant to various types of standard physicochemical inactivation. We suggest that CJD agents are either constituted by retroviral-like nucleic acids or interact with endogenous retroviral sequences to elicit a slowly progressive disease of the central nervous system. Several overlapping properties between infectious CJD and 'non-infectious' dementias, such as Alzheimer's disease, implicate potential common pathogenic mechanisms.

A new genetic disorder in mitochondrial fatty acid beta-oxidation: ACAD9 deficiency

The acyl-CoA dehydrogenases are a family of multimeric flavoenzymes that catalyze the alpha,beta -dehydrogenation of acyl-CoA esters in fatty acid beta -oxidation and amino acid catabolism. Genetic defects have been identified in most of the acyl-CoA dehydrogenases in humans. Acyl-CoA dehydrogenase 9 (ACAD9) is a recently identified acyl-CoA dehydrogenase that demonstrates maximum activity with unsaturated long-chain acyl-CoAs. We now report three cases of ACAD9 deficiency. Patient 1 was a 14-year-old, previously healthy boy who died of a Reye-like episode and cerebellar stroke triggered by a mild viral illness and ingestion of aspirin. Patient 2 was a 10-year-old girl who first presented at age 4 mo with recurrent episodes of acute liver dysfunction and hypoglycemia, with otherwise minor illnesses. Patient 3 was a 4.5-year-old girl who died of cardiomyopathy and whose sibling also died of cardiomyopathy at age 21 mo. Mild chronic neurologic dysfunction was reported in all three patients. Defects in ACAD9 mRNA were identified in the first two patients, and all patients manifested marked defects in ACAD9 protein. Despite a significant overlap of substrate specificity, it appears that ACAD9 and very-long-chain acyl-CoA dehydrogenase are unable to compensate for each other in patients with either deficiency. Studies of the tissue distribution and gene regulation of ACAD9 and very-long-chain acyl-CoA dehydrogenase identify the presence of two independently regulated functional pathways for long-chain fat metabolism, indicating that these two enzymes are likely to be involved in different physiological functions.

The effect of limited overfeeding during growth on muscle characteristics: a pig model

Energy restriction affects the hypothalamus, leading to a decrease in production of reproductive and thyroid hormones. A decrease in reproductive hormones affects fertility and a decrease in thyroid hormones affects muscle metabolism. A pig model has been used to determine that reproductive function is negatively affected if the normal practice of overfeeding is limited during the late luteal phase of the estrous cycle. We used a sub-set of pigs from this study to examine effects of limiting overfeeding on thyroid hormones and skeletal muscle (i.e. maximal enzyme activities, and muscle fibre characteristics). Eighteen rapidly growing gilts were randomized into three groups: 1) feeding a high plane of nutrition throughout the first 15 days of the estrous cycle; 2) limited overfeeding (25% below the first group) for first 7 days of the estrous cycle (early luteal phase), followed by a high plane of nutrition for days 8-15 (late luteal phase); and 3) high plane of nutrition throughout the first 7 days of the estrous cycle, followed by 8 days of limited overfeeding. Muscle biopsies were collected from the triceps brachii, and blood samples were collected for assessment of thyroid hormones at days 0 (baseline), 8 and 16. There was no effect of limited overfeeding on thyroid hormones, maximal enzyme activities, muscle fibre area or muscle fibre type. Limited overfeeding in rapidly growing pigs does not affect thyroid hormone status or muscle characteristics.

Effect of aminophylline on metabolic and thermoregulatory responses during hypothermia associated with cold exposure in lambs

Three experiments were conducted with lambs to test the hypothesis that the phosphodiesterase inhibitor/adenosine blocker, aminophylline would enhance metabolic rate and delay the development of hypothermia. In exp. 1, eight lambs were treated either with aminophylline or control (0.9% saline) injections. During hypothermia, metabolic rate was increased from a resting value of 4.8 W kg-1 to maximum values of 15–16 W kg-1. The rate of development of hypothermia and recovery there from were inversely related to age and body weight. Aminophylline (8 mg kg-1) did not affect resting or maximum metabolic rate, but after a second injection, aminophylline increased metabolic rate after warming (P < 0.05) and tended to shorten the absolute period of time to restore normal rectal temperature (P < 0.10). In exp. 2, a dose-response trial with six lambs each receiving 0, 2, 16 or 32 mg aminophylline indicated that dose rates of 16 and 32 mg kg-1 increased (P < 0.05) metabolic rate of lambs. In exp. 3, 21 lambs received either 0.9% saline or aminophylline (24 mg kg-1) injections. Mean heat production ranged from 13 to 15 W kg-1 and was increased approximately 7% (P < 0.01) by aminophylline. Aminophylline, therefore, has some potential as a treatment for hypothermia or to improve recovery from hypothermia in lambs by increasing metabolic rate during cold stress. Key words: Lamb, metabolic rate, hypothermia, thermoregulation, Aminophylline®, phosphodiesterase inhibitor

Changes in premorbid brain volume predict Alzheimer's disease pathology

OBJECTIVE

To assess whether changes in antemortem MRI brain volume measurements are valid predictors of subsequent Alzheimer disease (AD) pathology.

METHODS

Thirty-nine subjects, 15 nondemented and 24 with cognitive impairment, were followed until death. Regional postmortem measures of senile plaque (SP) and neurofibrillary tangle (NFT) severity were examined in relationship to cross-sectional and longitudinal volumetric measurements obtained from antemortem MRI.

RESULTS

Total brain volume change over time was related to the accumulation of cortical NFT. The rate of ventricular CSF volume increase was related to both cortical NFT and SP. The last hippocampal volume prior to death was related to hippocampal NFT burden; the rate of hippocampal volume atrophy was not related to hippocampal NFT pathology. These significant relationships continue to exist when all nondemented subjects are excluded from analysis. In subjects with cognitive impairment, the best predictor of cortical NFT and SP is the rate of ventricular volume increase. Excluding subjects with long duration between MRI and death did not appreciably alter results.

CONCLUSIONS

MRI volumes measured over time are valid biomarkers of pathologic progression of AD across a range of antemortem clinical states. The rate of ventricular volume enlargement can be used to monitor disease progression or response to treatment in future clinical trials that are targeted at NFT and SP pathology.

Expression of alpha-synuclein in the human brain: relation to Lewy body disease

Alpha-synuclein is mutated in some hereditary cases of Parkinson's disease and the protein precipitates in Lewy bodies, the pathological hallmark of both Parkinson's disease and Lewy body disease. Transgenic mice overexpressing human wild-type alpha-synuclein develop alpha-synuclein-immunoreactive inclusions in brain regions typically affected with Lewy body disease. We used in situ hybridization to characterize alpha-synuclein expression and examine mRNA levels in patients affected with Lewy body disease and controls. Substantia nigra was avoided because of the extensive neuronal loss and cingulate gyrus was chosen as it is one of the diagnostic regions in Lewy body disease where Lewy bodies most frequently are demonstrated. beta-tubulin was used to control for neuronal degeneration. The alpha-synuclein probe showed intense labeling of pyramidal cells in lamina III and V in both patients and controls. We found no difference in alpha-synuclein mRNA levels and beta-tubulin mRNA was not significantly altered (P=0.06) in patient brains. There was no difference in the ratio of alpha-synuclein and beta-tubulin mRNA levels between patients and controls. Further, we found no relationship between alpha-synuclein mRNA levels and Lewy bodies. Great variability in alpha-synuclein mRNA levels among patients indicates that Lewy body disease may be a heterogeneous disorder with regard to alpha-synuclein involvement.

Functional electrical stimulation exercise increases GLUT-1 and GLUT-4 in paralyzed skeletal muscle

The study purpose was to determine the effect of functional electrical stimulation (FES)-leg cycle ergometer training (30 minutes on 3 d/wk for 8 weeks) on the GLUT-1 and GLUT-4 content of paralyzed skeletal muscle. Biopsy samples of vastus lateralis muscle were obtained pre- and post-training from five individuals with motor-complete spinal cord injury ([SCI] four men and one woman aged 31 to 50 years, 3 to 25 years postinjury involving C5-T8). Western blot analysis indicated that GLUT-1 increased by 52% and GLUT-4 increased by 72% with training (P < .05). This coincided with an increase in the muscle oxidative capacity as indicated by a 56% increase in citrate synthase (CS) activity (P < .05) and an improvement in the insulin sensitivity index as determined from oral glucose tolerance tests (P < .05). It is concluded that FES endurance training is effective to increase glucose transporter protein levels in paralyzed skeletal muscle of individuals with SCI.

Apolipoprotein E epsilon4 is associated with neuronal loss in the substantia nigra in Alzheimer's disease

Apolipoprotein E epsilon4 (ApoE epsilon4) is associated with an earlier age at onset of Alzheimer's (AD) and possibly Parkinson's disease, suggesting a general role for ApoE epsilon4 in neuronal plasticity. Among 31 prospectively assessed subjects with pathologically confirmed AD (without Lewy bodies), epsilon4+ subjects had a longer duration of disease (by 2.8 years, p = 0.04). Only cell loss in the substantia nigra (p = 0.002) was associated with epsilon4. Neither neurofibrillary tangles nor plaque counts were associated with epsilon4. Cell counts of pigmented neurons in single midbrain sections in epsilon4+ specimens were 72% of those in epsilon4- substantia nigra (p = 0.04). These findings confirm that cell loss in the substantia nigra is associated with epsilon4 in AD. Copyrightz1999S.KargerAG,Basel

Implementation and evaluation of a measles/rubella vaccination campaign in a campus university in the UK following an outbreak of rubella

An age shift in rubella infection to young adults has occurred in Scotland since the introduction of a first dose measles, mumps and rubella (MMR) vaccination in 1988 and a second dose measles/rubella (MR) vaccination in 1994/95. The Health Board was alerted to an outbreak of rubella at Stirling University by the notification of 6 cases amongst male students aged 18-28 years with dates of onset between 3 March and 21 March 1996. In response, a MR vaccination campaign was conducted to enhance population immunity to rubella within the university population and to reduce the likelihood of further cases. A total of 1795 students, staff and visitors were vaccinated. Vaccine coverage of 46% was estimated to be sufficient to boost rubella immunity in full time male students in university accommodation to 88.7-91.0%, just above the upper critical level of herd immunity for rubella of 85-88%. Students in colleges and universities in the UK will remain at increased risk of outbreaks of rubella and measles until the cohort who have received a two dose schedule of MR form the bulk of the college population. It may be prudent for tertiary education colleges and other institutions in the UK with young adults living in shared residential accommodation to offer MR vaccination to new entrants, targeting those who have not previously received the vaccine, between now and the year 2000.

Potentiation of agonist-stimulated cyclic AMP accumulation by tyrosine kinase inhibitors in rat pinealocytes

To study cross-talk mechanisms in rat pinealocytes, the role of tyrosine kinase or kinases in the regulation of adrenergic-stimulated cyclic AMP production was investigated. Both norepinephrine- and isoproterenol-stimulated cyclic AMP accumulation were increased by two distinct tyrosine kinase inhibitors, genistein or erbstatin, in a concentration-dependent manner. A similar increase was observed with two other inhibitors, tyrphostin B44 and herbimycin. In contrast, daidzein, an inactive analogue of genistein, was ineffective; whereas vanadate, a phosphotyrosine phosphatase inhibitor, reduced the adrenergic-stimulated cyclic AMP accumulation. The tyrosine kinase inhibitors were effective in potentiating the cholera toxin-or forskolin-stimulated cyclic AMP accumulation, indicating that their sites of action are at the postreceptor level. Neither an activator nor inhibitors of protein kinase C influenced the potentiation of the cyclic AMP responses by genistein, suggesting that the potentiation effect by tyrosine kinase inhibitors does not involve the phospholipase C/protein kinase C pathway. However, when the phosphodiesterase was inhibited by isobutylmethylxanthine, genistein failed to potentiate and vanadate did not inhibit the adrenergic-stimulated cyclic AMP accumulation, indicating that the phosphodiesterase is a probable site of action for these inhibitors. These results suggest that cyclic AMP metabolism in the pinealocytes is tonically inhibited by tyrosine kinase acting on the cyclic AMP phosphodiesterase.

Tyrosine kinase inhibitors enhance cGMP production in rat pinealocytes

The role of tyrosine kinase(s) in the regulation of cGMP accumulation in rat pinealocytes was investigated using three tyrosine kinase inhibitors. Treatment with genistein, erbstatin or the active analogues of tyrphostin selectively increased basal cGMP accumulation in a dose-dependent manner without a concomitant increase in cAMP. In contrast to the norepinephrine- and vasoactive intestinal peptide-stimulated cGMP responses, the stimulatory effect of genistein was not blocked by the nitric oxide synthase inhibitor NG-monomethyl-L-arginine. Furthermore, in the presence of isobutylmethylxanthine, a phosphodiesterase inhibitor, neither genistein nor erbstatin had an effect on cGMP accumulation. These results indicate that tyrosine kinase inhibitors increase pineal cGMP accumulation through inhibition of the metabolism of cGMP.

Molecular characterization of a protein-tyrosine-phosphatase enriched in striatum

A cDNA clone encoding a neural-specific putative protein-tyrosine-phosphatase (protein-tyrosine-phosphate phosphohydrolase, EC 3.1.3.48) has been isolated from a rat striatal cDNA library. The deduced amino acid sequence predicts a protein of approximately 369 amino acids with a strong homology to other members of the family of protein-tyrosine-phosphatases. In vitro translation produces a protein with an apparent molecular mass of 46 kDa. A potential attachment mechanism to the cytoplasmic membrane is suggested by a myristoylation amino acid-consensus sequence at the N terminus of the protein. RNA analyses of various regions of rat brain reveal a 3-kilobase (kb) and a 4.4-kb mRNA. The 3-kb mRNA is highly enriched within the striatum relative to other brain areas and has been termed a "striatum enriched phosphatase" (STEP). In contrast, the 4.4-kb message is most abundant in the cerebral cortex and rare in the striatum. These two messages appear to be alternatively processed RNA transcripts of a single gene.

Further experience in the healing rate of lower limb amputations

Results of lower limb amputation in the Tayside Region in the years 1981-1985 have been analysed. Three-hundred and twenty-four amputations were performed on three-hundred and eight patients. Two-hundred and thirty-six amputations were attempted at the below-knee level. Only 19 required proximal revision. Prior to amputation, all patients should have a detailed vascular assessment, and the operation should be performed by experienced amputation surgeons using meticulous technique.

Growth factor production by Creutzfeldt-Jakob disease cell lines

Creutzfeldt-Jakob disease (CJD), a progressive dementia of humans, is caused by an infectious agent that is closely related to the scrapie agent of sheep. Although the molecular nature of these "unconventional" agents is still a matter of speculation and controversy, even less is known concerning the mechanism(s) of their effects on the central nervous system. To gain insight into the cellular effects of these agents, we have examined a series of cell lines derived directly from CJD-infected hamster brain or produced from nontransformed rodent lines by exposure to CJD infectious fractions in vitro. These cell lines appear transformed by a variety of criteria and secrete growth factors into the culture medium. All CJD lines produce a factor that is like alpha-transforming growth factor (alpha-TGF). Conditioned medium from these CJD lines also stimulates the synthesis of glial fibrillary acidic protein in normal astrocytic cells in vitro. This effect is mimicked by purified alpha-TGF and platelet-derived growth factors. Further study of CJD-induced growth factor production may elucidate fundamental properties of these unconventional agents.

Fate of the vascular patient after below-knee amputation

50 below-knee amputations were carried out in 45 patients (25 men and 20 women), mean (SD) age 73 (10.5) years. The mean survival time was 22(16) months after the operation. In each patient the healing potential of a below-knee amputation was determined preoperatively by segmental pressure studies and thermographic delineation of skin perfusion. 33 of the stumps healed by first intention, in 14 healing was delayed but occurred without the need for further surgery, and 3 stumps healed after local wedge excision. The initial mobilisation rate was 90%. Thus, there are no grounds for carrying out an initial above-knee amputation to save the patient a further operation.

Decrease in human quadriceps muscle protein turnover consequent upon leg immobilization

Quadriceps muscle protein turnover was assessed in the post-absorptive state in six men immediately after the end of unilateral leg immobilization (37 +/- 4 days) in a plaster cast after tibial fracture. A primed-constant intravenous infusion of L-[1-13C]leucine was administered over 7 h. Quadriceps needle biopsies, taken bilaterally at the end of the infusion, were analysed for muscle protein leucine enrichment with 13C. Quadriceps muscle protein synthetic rate, calculated from the fractional incorporation of [13C]leucine into protein compared with the average enrichment of blood alpha-ketoisocaproate, was 0.046 +/- 0.012%/h in the uninjured leg, but was only 0.034 +/- 0.007%/h in the quadriceps of the previously fractured leg (P less than 0.05, means +/- SD). Muscle RNA activity (i.e. protein synthetic rate per RNA) fell from 0.27 +/- 0.08 microgram of protein synthesized h-1 microgram-1 of RNA in the control leg to 0.14 +/- 0.03 microgram of protein synthesized h-1 microgram-1 of RNA in the immobilized leg (P less than 0.02). Immobilization was associated with a significant atrophy of type I muscle fibres (mean diameter 69.5 +/- 21 microns immobilized, 81.1 +/- 18 microns control, P less than 0.05), but no significant change occurred in type II fibre diameter. Mean quadriceps fibre volume calculated from the values for fibre diameter and percentage of each fibre type, was smaller in the injured leg by 10.6%; this value was near to the calculated difference in muscle thigh volume (calculated from thigh circumference and skin-fold thickness) which was less by 8.3%.(ABSTRACT TRUNCATED AT 250 WORDS)

Wedge resection of amputation stumps. A valuable salvage procedure

We describe the technique of wedge resection for revision of an amputation stump, and report the results of this at below-knee level in 57 patients with peripheral vascular disease; healing occurred in 42 of these (74%).

The pharmacokinetics of R- and S-tocainide in patients with acute ventricular arrhythmias

The pharmacokinetics of R(-) and S(+)- tocainide were studied in twelve patients requiring intravenous tocainide. In all patients, a progressive increase in the S(+):R(-) ratio was observed during the infusion. Mean +/- s.d. ratios increased from 1.03 +/- 0.05 at 2 min to 1.76 +/- 0.35 at 48.5 h. Data from eight patients were fitted to a two-compartment model and there was a significant difference (Wilcoxon matched-pairs test P less than 0.01) in the clearance estimates for the two enantiomers. The median values were: S(+)-tocainide = 6.25 l h-1 and R(-)-tocainide = 9.31 l h-1. There was no differences in V1 or Vss.

A rationale for skew flaps in below-knee amputation surgery

The use of thermography in the assessment of amputation levels has demonstrated a medial to lateral thermal gradient in many cases. In order to see whether this reflected a true medial to lateral skin blood flow gradient, a prospective study was set up to measure blood flow medially and laterally below the knee. Twenty-one patients, presenting for amputation assessment with end-stage peripheral vascular disease, were studied. Skin blood flows were measured using an intradermal radioisotope clearance technique. Results showed a highly significant difference between medial and lateral skin blood flows (t = 4.79; p less than 0.001). In view of the significantly higher blood flow in the medial skin of the lower leg, it is suggested that a more medially based posterior below-knee amputation skin flap may be of more value in some patients.

In defence of gait analysis. Observation and measurement in gait assessment

The gait pattern of five amputees was recorded by visual observation and also by a quantitative measurement system. The results were compared with the gait pattern predicted from biomechanical analysis. Visual observation was found to be an unreliable clinical skill. The observers recorded only 22.2% of the predicted gait deviations and were unable to comment on 15.6% of all the required observations. The gait parameters which were difficult to assess visually, namely step length and step time, are considered by most workers to be of particular value as diagnostic clinical indicators in gait assessment. The measurement system used was accurate in recording gait deviations and picked up 3.4 times as many deviations as visual observation. This report demonstrates the inadequacy of visual observation as a diagnostic method and emphasises the need for measurements.

Assessment of tissue viability in relation to the selection of amputation level

Assessment of the optimum level of amputation of an ischaemic limb can be exceptionally difficult. For this reason there has been an intensive effort, particularly in the past 20 years, to find suitable non-invasive ancillary methods to aid in the amputation level selection. This paper reviews three separate research and development areas which have evolved simultaneously in our laboratory: skin partial oxygen pressure, skin blood flow, and infrared thermography. The physiological basis for each of these measurements is discussed along with the merits and demerits of each.

Haemarthrosis of the knee joint

One hundred and twenty knee injuries diagnosed as traumatic haemarthrosis were reviewed. All were initially treated by aspiration and splintage. None had major ligamentous or major bony injury clinically or radiographically when first seen. The incidence of anterior cruciate damage was 17 per cent and that of crack fracture was 29 per cent. Many of those aged under thirty had anterior cruciate damage. Those over thirty commonly had crack fractures. Sixty-five per cent of the patients had no symptom when reviewed. A total of 9.9 per cent needed further operations. The younger patients, especially those with an injury from sport, should be referred to a specialist knee clinic for further management.

The postoperative environment of the amputation stump. Postoperative wound dressing after through-knee amputation

This paper reviews different types of treatment of the amputation stump. Following an examination of the historical development there are sections on bandaging, semi-rigid dressings, rigid cast dressing and controlled environment treatment. The merits and demerits of each type of treatment are discussed.

Fractured neck of femur. Pattern of incidence and implications

Projected figures for the 1975 incidence of fracture neck of femur in Dundee are compared with the actual figures. Analysis of the incidence in 1952, 1975 and 1980, relating it to age and other factors, shows both an increase in the true incidence and a marked rise in the total number over the period. The length of stay in an Orthopaedic ward is considerably increased if the patient then has to be admitted to a long-stay bed. This length of inpatient stay and the increased incidence continues to raise the demand on acute Orthopaedic female beds.

Amputation of the ischemic limb: selection of the optimum site by thermography

This report describes the value of infrared thermography in assessing the optimum level of amputation of an ischemic limb. Interpretation of thermograms and the factors that can significantly alter the thermal image of the lower limbs are detailed. Results from 104 patients demonstrate that the thermographic method is a reliable indicator of the level of a major limb amputation. A rationale for the inadequacy of the method when attempting to determine the outcome of a partial foot amputation is considered.

Levels of amputation and limiting factors

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