The effect of carbohydrate mouth rinsing on fencing performance and cognitive function following fatigue-inducing fencing.

This study investigated the impact that mouth rinsing carbohydrate solution has on skill-specific performance and reaction time following a fatigue-inducing bout of fencing in epee fencers. Nine healthy, national-level epee fencers visited a laboratory on two occasions, separated by a minimum of five days, to complete a 1-minute lunge test and Stroop test pre- and post-fatigue. Heart rate and ratings of perceived exertion (RPE) were recorded during completion of the fatiguing protocol. Between fights the participant's mouth rinsed for 10 seconds, either 25 ml of 6.7% maltodextrin solution (MALT) or water (PLAC). Blood lactate and glucose were recorded at baseline, pre- and post-testing. Results showed an increase in heart rate and overall RPE over time in both conditions. There were no differences in blood glucose (F(1,8) = .63, P = .4, ηp = .07) or blood lactate levels (F(1,8) = .12, P = .70, ηp = .01) between conditions as a function of time. There was a significant improvement in lunge test accuracy during the MALT trial (F(1,8) = 5.21, P = .05, ηp = .40) with an increase from pre (81.2 ± 8.3%) to post (87.6 ± 9.4%), whereas there was no significant change during the placebo (pre 82.1 ± 8.8%, post 78.8 ± 6.4%). There were no recorded differences between conditions in response time to congruent (F(1,8) = .33, P = .58, ηp = .04) or incongruent stimuli (F(1,8) = .19, P = .68, ηp = .02). The study indicates that when fatigued mouth rinsing MALT significantly improves accuracy of skill-specific fencing performance but no corresponding influence on reaction time was observed.

Brain morphometry and IQ measurements in preterm children.

Although IQ is thought to remain relatively stable in the normal population, a decline in IQ has been noted in children born preterm. It is not clear, however, to what extent the inclusion of children with clear neurological damage has influenced these findings. We examined IQ scores obtained in childhood and then again in adolescence from a group of children born at 30 weeks gestation or less who had been classified as neurologically normal at 7.5-8 years. They showed a significant decline in mean IQ scores over time. MRI scans obtained from a subset of children at adolescence were read as normal in approximately 50% of cases and, in the others, there were no consistent relationships between radiological abnormalities and IQ results. Such children can, however, have relatively subtle brain abnormalities that are not seen on conventional MRI, and we hypothesized that these would be related to declines in IQ. Voxel-based morphometry (VBM) analyses of the MRI scans revealed that absolute IQ scores were related to areas in both the parietal and temporal lobes. The analyses also showed that frontal and temporal lobe regions were associated with the decline in VIQ, while occipital and temporal lobe regions (including the hippocampi) were associated with the decline in PIQ. Hippocampal volume measurements were consistent with the VBM findings. We concluded that preterm children are at risk of declining IQ over time even if they have not suffered obvious neurological damage and that the decline is associated with specific neural regions. Whether this is true of children born at >30 weeks gestation and what other factors predispose to this decline have yet to be determined.

Calculation difficulties in children of very low birthweight: a neural correlate.

Learning difficulties, including problems with numeracy, are common in Western populations. Many children with learning difficulty are survivors of preterm birth. Although some of these children have neurological disabilities, many are neurologically normal, and the latter group provides us with an important opportunity to investigate the neural bases of learning problems. We have conducted a neuroimaging study of adolescent children who had been born preterm at 30 weeks gestation or less, to investigate the relationship between brain structure and a specific difficulty in arithmetic calculation. Using voxel-based morphometry, we have been able to demonstrate that there is an area in the left parietal lobe where children without a deficit in calculation ability have more grey matter than those who do have this deficit. To our knowledge, this is the first report establishing a structural neural correlate of calculation ability in a group of neurologically normal individuals.

Treatment of Graves' disease by carbimazole: high dose with thyroxine compared to titration dose.

A comparative study of high-dose (HD, carbimazole 60 mg plus thyroxine 100-150 micrograms daily) and titration-dose (TD) regimens of carbimazole was carried out in 70 patients with Graves' disease, the patients being assigned randomly to one or other regimen. The treatment was given for 1 year and follow-up was for 2 years after stopping treatment. In both groups, recurrence of hyperthyroidism occurred, most commonly during the first 6 months (35% of HD and 44% of TD). By 2 years after stopping treatment, recurrence had occurred in 50% of the HD and 66% of the TD group. The differences were not significant. Thyroid antibodies, serum thyroglobulin and pertechnetate uptake fell similarly in both groups during treatment. Cigarette smoking was similar in both the groups and did not influence the frequency of relapse. In both HD and TD groups, when relapsing patients were examined according to whether they relapsed early (within 6 months or less) or late it was found that those who relapsed late were, in respect of goitre size, pertechnetate uptake and presence of detectable plasma TSH, similar to the patients who did not relapse at all. In conclusion, the changes in the measured variables and the progress of the patients was similar whether treated by the HD or TD regimen.

US-Canada Great Lakes Regional Specimen Bank Feasibility Study.

A study to examine the feasibility of establishing a Regional Specimen Bank in the Great Lakes area of the United States and Canada has recently been initiated by the Michigan Audubon Society. There are several existing formal and informal specimen banking facilities active in the region but their combined adequacy has not been evaluated. This feasibility study will establish the need and use of a regional bank and the institution(s) necessary to satisfy this need will be recommended. The study will address the scope required to meet present and future needs including the types of specimens to be represented in the bank, geographic coverage and protocols for collection, shipping, processing, analysis and storage. A management policy of the bank will be developed encompassing business operation, costs, governing structure and personnel requirements. The legal requirements of the bank will be determined with regards to the acquisition of samples, transport across national boundaries, access to specimens and information, and liability during operation. An effective information dissemination network will be recommended that is compatible with national and international partners, will facilitate technology and information transfer and support the quality and status of the bank. Determination of secure, long-term funding sources will be one of the key elements to ensuring a safe repository. This feasibility study is funded by the Great Lakes Protection Fund.

Deficiency of 17 alpha-hydroxylase associated with absent gonads.

A phenotypic female presented initially at the age of 17 years with amenorrhoea and delay of sexual development. Karyotype was male, 46 XY, and as gonads were absent, a diagnosis of congenital anorchia was made. The patient was treated with oestrogen. At the age of 23 years, she re-presented with tall stature and hypertension. She then had normal female habitus but absent pubic and axillary hair. Re-investigation showed that sex steroids and cortisol were absent and established the diagnosis as 17 alpha-hydroxylase deficiency. Treatment with hydrocortisone rapidly corrected the hypertension. Ultrasound examination confirmed the absence of gonads but showed that a small uterus was present. Measurement of serum cortisol is important for recognition of such patients, but further measurements of sex steroids, particularly progesterone, are needed to prove the diagnosis. We have found no previous reports of absent gonads in 17 alpha-hydroxylase deficiency. The association remains unexplained.

A pre-eclamptic-like syndrome associated with hypothyroidism during pregnancy.

Hypothyroidism presenting during pregnancy is rare, probably due to the lower incidence of hypothyroidism during the reproductive years, and because myxoedema causes anovulatory cycles. We report an unusual case of hypothyroidism during a 34-year-old woman's fifth pregnancy, complicated by hypertension, oedema, pericardial effusion and severe nephrotic syndrome. This is the first report of renal biopsy abnormalities under these circumstances. Review of the literature regarding hypothyroidism presenting during pregnancy leads us to suggest that hypothyroidism during pregnancy may mimic pre-eclampsia.

Comparison of fine needle aspiration cytology, radioisotopic and ultrasound scanning in the management of thyroid nodules.

In 175 patients presenting with thyroid nodules, the diagnostic value in management of fine needle aspiration and cytology (FNAC), pertechnetate (99mTc) scanning and ultrasound imaging was examined. In 82 patients, the diagnosis was confirmed at operation; in the remaining 93, there was a follow-up period of at least 2 years. Thyroid cancer was found in 13 patients. For FNAC the sensitivity, specificity and positive predictive value for thyroid cancer were 92%, 85% and 41% respectively compared with 82%, 34% and 11% for 99mTc pertechnetate scanning, 75%, 61%, 19% for ultrasound and 73%, 58% and 19% for combined pertechnetate and ultrasound scanning. In 14% of patients, the aspirates were inadequate for cytology at the first examination. FNAC is therefore the preferable initial investigation and usually gives results adequate for a decision on surgical or medical management. With medical management and follow-up, ultrasound is of value in defining the nodule and the appearance of the rest of the gland.

The effect of dietary sodium and potassium intake on potassium secretion and kinetics in rat distal colon.

1. Potassium secretion by the distal colon was examined in relation to the secretion of chloride and absorption of sodium and to the epithelial turnover of 86Rb+ (as an analogue of potassium) in vivo in rats fed a standard, a potassium-rich or a sodium-depleted diet. 2. An acute intravenous potassium load stimulated potassium secretion two- to threefold. In rats fed the standard diet, sodium secretion was also increased but no significant change in the lumen-to-plasma sodium flux was detected. The potassium and sodium secretions were accompanied by increased chloride secretion which occurred even when the intravenous load contained no chloride. In rats fed the potassium-rich diet, there was a small increase in sodium absorption and a less marked increased of chloride secretion. In the sodium-depleted rats, however, about 70-80% of the increased potassium secretion was balanced by increased sodium absorption. 3. The epithelial turnover rate of 86Rb+ in the rats fed the potassium-rich (t1/2 12-14 min) and the sodium-depleted (t1/2 11-13 min) diets was faster than that of those of the standard diet (t1/2 22-27 min). 4. The epithelial potassium content was 304 +/- 9 nmol (mg dry weight)-1 and was not significantly altered despite considerable variations in potassium secretion rate induced by dietary changes and acute potassium loading. 5. It is concluded that epithelial potassium turnover rate is increased during chronic states of increased potassium secretion and that the rise in potassium secretion is consistent with increased activity of the basolateral Na(+)-K+ pump. Whether the increased potassium secretion is associated with chloride secretion or with increased sodium absorption appears to depend on the absence or presence of the amiloride-sensitive sodium pathway in the apical membrane.

Aldosterone and thyroid hormone interaction on the sodium and potassium transport pathways of rat colonic epithelium.

The effect of hypothyroidism on potassium adaptation (shown by increased potassium secretion in response to potassium loading) and on the action of aldosterone on potassium secretion and sodium fluxes was examined in the rat distal colon. Potassium adaptation, particularly the response to an acute potassium load, was impaired by hypothyroidism which also considerably reduced the rise of transepithelial electrical potential difference (p.d.) of total and transcellular (active) lumen-to-plasma sodium fluxes and of potassium secretion normally produced by aldosterone. These changes were, in part, corrected by a short period (3 days) of tri-iodothyronine replacement. Moreover in aldosterone-treated hypothyroid rats, amiloride in the lumen was considerably less effective in reducing the p.d. and sodium fluxes than in aldosterone-treated normal rats. The intracellular sodium transport pool was greater in the hypothyroid than in the normal rats (5.0 +/- 1.1 (S.E.M.) nmol/mg dry weight compared with 2.9 +/- 0.2 nmol/mg dry weight; P less than 0.02). Aldosterone increased the pool in the normal but not in the hypothyroid rats while amiloride had little effect on the pool in the aldosterone-treated hypothyroid rats but almost abolished it in aldosterone-treated normal rats. Aldosterone plays a major part in the adaptation of colonic sodium and potassium transport to sodium depletion or potassium excess; these adaptations were much impaired in hypothyroid animals. The present results are consistent with a deficiency in aldosterone induction of potassium- and amiloride-sensitive sodium pathways in the apical membrane of colonic epithelial cells in hypothyroid rats, a deficiency which limits the stimulant effect of aldosterone on sodium and potassium transport.

Nickel deficiency gives rise to the defective hydrogenase phenotype of hydC and fnr mutants in Escherichia coli.

Hydrogenase activity and other hydrogenase-related functions can be restored to hydC mutants by the specific addition of nickel salts to the growth medium. These mutants are defective in all three hydrogenase isoenzymes and the restoration is dependent upon protein synthesis. The cellular nickel content of the mutant when grown in LB medium is less than 1% of that of the parental strain. Partial suppression of the hydrogenase phenotype of hydC mutants occurs when growth takes place in a different medium. This correlates with an increased cellular nickel content. The phenotype of the mutant is also fully suppressed by growth in media of very low magnesium content. Such media facilitate nickel uptake via the magnesium transport system, which leads to the acquisition of a normal cellular nickel content. Mutations in the fnr gene, which encodes a transcriptional regulator for several anaerobically expressed enzymes, abolishes hydC expression and gives rise to a defective hydrogenase phenotype. The hydrogenase phenotype of fnr is closely similar to that of hydC in all respects examined. The hydrogenase activity of fnr strains can be restored by the presence of a functional hydC gene on a multicopy plasmid. The hydrogenase phenotype of fnr strains therefore arises indirectly via suppression of hydC, which leads to a low cellular nickel content. Nickel has no influence on fumarate reductase or nitrate reductase activities in fnr strains. The hydrogen-metabolism phenotype of fnr strains is, therefore, dependent upon their ability to acquire nickel from growth media. It is likely that hydC encodes a specific transport system for nickel.

Potassium secretion by rat distal colon during acute potassium loading: effect of sodium, potassium intake and aldosterone.

1. Potassium secretion by the distal colon before and during intravenous infusion of a potassium load was measured in vivo in groups of rats treated in various ways: A, normal control; B, adrenalectomized; C, sodium depleted; D, on potassium-rich diet for 7 days; E, after 72 h aldosterone (1 microgram/h); F, after 72 h aldosterone (10 micrograms/h). 2. Potassium infusion produced no increase of secretion in the adrenalectomized rats but in all the other groups it increased by 2- to 3-fold. Secretion during infusion correlated well with the basal (pre-infusion) rate and in groups C and D reached 140 +/- 15 and 173 +/- 17 nmol min-1 cm-1 respectively compared with 28 +/- 6 nmol min-1 cm-1 in the controls (A). The passive paracellular pathway for potassium was unaffected by the infusion. Amiloride (100 mumol/l) did not significantly affect potassium secretion rate either before or during the acute potassium infusion. The potassium channel blocker, tetraethylammonium chloride, reduced both basal and the secretion rate during infusion. 3. Transepithelial potential difference (PD), active sodium absorption and sodium fluxes were similar in normal controls and rats fed the potassium-rich diet. However, the PD was partially amiloride sensitive in the latter group although amiloride insensitive in the normal group. In sodium-depleted rats, the PD was elevated and totally amiloride insensitive. 4. In both aldosterone-treated groups (E and F), basal potassium secretion rate was high and similar, and during potassium infusion rose 3-fold to 114 +/- 24 (E) and 105 +/- 5 (F) nmol min-1 cm-1. However, the PD was not elevated significantly in group E and was only partially amiloride sensitive, whereas in those infused at the higher rate (F) the PD was increased and was totally amiloride sensitive. 5. The high potassium secretion rates developed by this epithelium in sodium-restricted and potassium-enriched dietary states appear to depend on the presence of an amiloride-insensitive transcellular potassium pathway which is induced at a lower level of aldosterone stimulation than is the amiloride-sensitive transcellular sodium pathway.

Aldosterone in colonic potassium adaptation in rats.

The influence of adrenalectomy and administration of aldosterone on potassium secretion by colonic epithelium was studied in vivo in rats, particularly in relation to potassium adaptation (induced by feeding a potassium-rich diet) and the response to acute i.v. administration of a potassium load. Adrenalectomy (rats maintained on dexamethasone and saline) impaired the development of potassium adaptation or considerably reduced it if the rats had been previously adapted. The partial adaptation observed in the adrenalectomized rats may be related to the increased plasma potassium concentration developed when these rats received the potassium-rich diet. Within 2 h of acute aldosterone administration, the response of the potassium secretion rate to acute potassium loading in adrenalectomized rats was significantly improved. When aldosterone (2 micrograms/day per 100 g body weight, given by osmotic minipump) was added to the replacement treatment, the plasma concentration of potassium was similar to that of the intact rats, and both potassium adaptation and the response to the acute potassium load were completely restored. Transepithelial potential difference and sodium transport were not stimulated, being similar to the values in intact rats. Considerable changes in potassium secretion induced by acute potassium loading did not significantly affect sodium transport. The findings suggest that the sodium and potassium epithelial pathways are, to a large extent, independently influenced by aldosterone. Aldosterone appears to be essential for complete adaptation and, in a relatively low dose, can completely restore potassium adaptation and the response to acute potassium loads in adrenalectomized rats.

Serum thyroglobulin in the investigation of patients presenting with metastases.

Serum thyroglobulin (Tg) is often very elevated in patients with metastatic thyroid carcinoma and, in 18 out of 40 patients examined, serum Tg was found to exceed 400 micrograms/l. In only two of 55 patients with benign nodular thyroid disease did serum Tg exceed 400 micrograms/l. In patients presenting with metastases of unknown origin, the finding of a very elevated serum Tg concentration may therefore be of value as an indicator that the metastases are due to thyroid carcinoma. During a period in which 128 new patients with differentiated thyroid carcinoma were seen, in five who presented with metastatic disease the initial estimation of serum Tg had proved useful in suggesting the thyroid origin of the metastases.

Hyperthyroidism and thyroid cancer.

Ten of 502 patients presenting with thyroid cancer were hyperthyroid due to Graves' disease (4 patients), multinodular goitre (3), an autonomous functioning nodule (1) and a large functioning tumour (2). In addition eight patients had a past history of Graves' disease and four of hyperthyroidism associated with multinodular goitre. Mortality in patients with Graves' disease and with multinodular goitre appeared similar to that of other patients of comparable age. Both patients with large functioning tumours died from progressive disease. Concentration 131I by tumour metastases was present in one patient with active Graves' disease who had a high serum concentration of TSH-receptor binding antibodies, indicating that these antibodies may chronically stimulate tumour function. The potential for 131I concentration by tumour when TSH secretion is suppressed should therefore be determined in patients with Graves' disease and if demonstrable tumour function is present, reflecting stimulation by Graves' immunoglobulins, then elimination of tumour remnants is particularly important.

Measurement of exchangeable sodium: 22Na or 24Na?

A case is made for the use of 22Na in low activities in preference to 24Na for routine diagnostic estimation of exchangeable sodium, and is based chiefly on considerations of availability, cost and radiation dosimetry. A method in which only 37 kBq (1 microCi) 22Na is administered orally is shown to be sufficiently accurate and to possess distinct advantages in terms of cost and convenience with a committed radiation dose no greater than that for a measurement using 24Na.

Sodium transport and the cellular sodium transport pool of colonic epithelium: effects of sodium loading, aldosterone and lithium.

The cellular sodium transport pool and sodium transepithelial fluxes were investigated in vivo in rat distal colon in relation to sodium loading by intravenous infusion (3.5 h), and to short (4 h) and prolonged (72 h) i.v. administration of aldosterone. Considerable natriuresis and increase in body sodium content were produced by the sodium load but there was no significant effect on the transcellular sodium flux (active absorption from lumen to plasma) or on the sodium transport pool. Both short and prolonged aldosteronism produced similar increases in the transport pool and in the transcellular sodium flux, but the transepithelial electrical potential difference (p.d.) was significantly greater in rats given the prolonged infusion. Addition of amiloride to the solution in the lumen of the colon almost completely abolished the p.d., the transport pool and the transcellular sodium flux of the rats receiving prolonged infusion, but had much less effect in those given the short infusion. The time-course of recovery of p.d. following prolonged aldosteronism was similar to that described for the turnover rate of rat colonic epithelial cells. Lithium within the lumen had no significant effect in untreated rats but after prolonged aldosterone infusion lithium reduced the p.d. and the transcellular sodium flux although the transport pool was not reduced. These findings are consistent with the hypothesis that aldosteronism renders the apical membranes of the epithelial cells permeable to lithium and that intracellular accumulation of lithium depresses active sodium transfer.(ABSTRACT TRUNCATED AT 250 WORDS)