Intake and blood levels of some minerals in an elderly Chinese population

Twenty-four hour intakes of potassium, calcium, and iron, and plasma concentration of potassium, copper and zinc were determined in a cluster sample of 400 apparently healthy subjects aged 60 years and over living in the community. Potassium and calcium intakes were lower in older men and lower in men compared to women. Both were much lower than intakes reported among Caucasian elderly, while iron intakes are comparable. Plasma potassium concentration was lower than values from studies of all ages and from studies of Caucasian elderly subjects. Copper and zinc concentrations were comparable to published values for adults of all ages. The significance of low potassium and calcium intake among elderly subjects in the population is discussed.

An in vitro comparison of different bleaching agents in the discolored tooth

Extracted teeth with intact crowns were stained to compare and evaluate the effectiveness of four bleaching agent combinations. Forty-two permanent and 12 deciduous teeth were used. The bleaching agents were placed into coronal pulp chambers and then evaluated and rated at 1-, 3-, 7-, and 14-day and 6-month intervals. New sodium perborate combined with fresh Superoxol was the most effective bleaching agent with 93% success (the final shade was as light as the prestained shade). New sodium perborate and 1-yr-old Superoxol was 73% successful. New sodium perborate with distilled water and old sodium perborate with distilled water were both 53% successful. Deciduous teeth demonstrated a response to bleaching agents similar to that of permanent teeth. Color regression after 6 months was found in 4% of the cases. When it occurred, the degree of color regression was minimal.

Vitamin A and E status in healthy elderly Chinese in Hong Kong

Daily intakes of retinol and beta-carotene equivalents, plasma retinol, retinol binding protein and plasma vitamin E were estimated in a cluster sample of apparently healthy elderly subjects aged 60 years and over in Hong Kong leading an active life in the community. Intakes were available from 418 and plasma measurements from 385 subjects. There were no age or sex differences in intakes. Plasma retinol and retinol binding protein levels showed no sex- or age-related difference, while plasma vitamin E levels were higher in women. Retinol binding protein, plasma retinol and plasma vitamin E levels were comparable to published values for Chinese and Caucasians of all ages. Vitamin A and E status appears to be adequate in this elderly Chinese population.

Forearm bone loss in hemiplegia: a model for the study of immobilization osteoporosis

Hemiplegia is associated with excessive bone loss in the paralyzed arm. The forearm bone mineral content was measured at a proximal cortical site and a distal trabecular site of both the normal and hemiplegic arms in 74 patients with hemiplegia. By comparing the ratios of bone mineral content in the two arms, the effect of immobilization could be quantitated independently of the large population variance in bone mineral content. Bone loss, estimated from this single comparison of bone mineral content in the normal and hemiplegic arms, at the trabecular and cortical sites was positively correlated with the duration of stroke and negatively correlated with reduction in forearm function. At the trabecular site females had a proportionately greater bone loss than males, indicating an interaction between gender and immobilization associated bone loss at this site. The regression line of excess bone loss in the hemiplegic limb against time had a negative slope of 1.3% and 1.5% a year of the starting value for the trabecular and cortical sites, respectively, over the 15 years studied. This study indicates that a reduction in function is associated with significant bone loss occurring over prolonged periods that may account, at least in part, for the significant osteoporosis seen in elderly people and in subjects with conditions resulting in reduced mobility such as arthritis, obstructive airways disease, and neurological disease.

The formation of topographical maps in developing rat gastrocnemius muscle during synapse elimination

1. The rat lateral gastrocnemius muscle (LG) is a complex of four muscle compartments, each defined in terms of its unique innervation by a single primary nerve branch of the muscle nerve. A study has been made of the topographical distribution of motor units in the medial compartment of the LG (LGM) both before and after the loss of polyneuronal innervation that accompanies development. 2. Glycogen depletion methods showed that the distribution of single motor units depended on the rostro-caudal origins of their axons in the spinal cord: rostral axons possessed motor units almost exclusively confined to the medial half of the LGM; intermediate axons possessed motor units primarily in the intermediate and lateral part of the LGM; caudal axons possessed motor units that were not restricted to any particular part of the LGM. 3. Myosin ATPase staining showed that about 80% of the LGM consists of type II A fibres, whilst the remainder are type II B. Physiological determination of the contractile properties of motor units indicated two classes of units: those that were relatively fatigue resistant and did not show a sag property (like fast-twitch, fatigue-resistant fibres or FR) and those that were relatively fatigable and did show a sag property (like fast-twitch, fatigable fibres or FF). 4. Glycogen depletion was also used to determine the distribution of motor units in the LGM at 7 days post-natal, when most fibres still receive a polyneuronal innervation. The LGM primary nerve branch innervated a confined sub-volume of muscle fibres which is similar to the mature pattern. However, rostral axons possessed motor units that extended into the lateral half of the LGM, a position from which they are excluded in the adult. 5. These observations suggest that the axons of rostral and intermediate units form a topographical map within adult FR motor units (type II A fibres) in the LGM. The results suggest that competition between axon terminals for synaptic sites plays a role in the elimination of inappropriately positioned terminals and subsequent emergence of the topographical map.

Cost-effectiveness of office obstetrical ultrasound in family practice: preliminary considerations

This study reports costs incurred over a nine-and-one-half-month period following the introduction of obstetrical ultrasound into a group family practice serving primarily prepaid health plan patients. During this introductory period, 248 examinations were performed by family physicians and refereed by a radiologist for accuracy. The estimated cost to the practice was $95 per examination. This figure includes physician training expenses, professional fees, personnel, equipment and maintenance costs, costs for exams repeated due to technical error, and costs for additional consultation by a radiologist. Previously, all exams were referred to other consultants, and the charge was $185 per exam. Thus, in-office ultrasound exams performed by family physicians can provide cost savings while maintaining high standards of obstetric care.

Osteoarthritis of the proximal interphalangeal joint

Most patients with symptomatic osteoarthritis of the proximal interphalangeal joint should be managed nonoperatively. When operative intervention becomes necessary, therapeutic options include joint fusion or flexible implant arthroplasty. Both relieve pain; however, an implant, while preserving mobility, is subject to fatigue and ultimate failure.

Competition between segmental nerves at end-plates in rat gastrocnemius muscle during loss of polyneuronal innervation

1. The segmental innervation of the rat lateral gastrocnemius (l.g.) muscle is from lumbar nerves L4 and L5. A study has been made of changes in the innervation of the l.g. muscle by nerves L4 and L5 before and after removal of L4 during the loss of polyneuronal innervation which occurs over the first 2 weeks postnatal. 2. The rat l.g. muscle is a complex of three unipennate muscles; the lateral, intermediate and medial heads. Each of these has a characteristic distribution of type I and type II muscle fibres of different diameter by 12 days postnatal. Following the removal of nerve L4 at birth there is no change in the distribution of fibre types in the different heads of the l.g. muscle at 12 days postnatal. 3. The number of fibres in the l.g. muscle doubled between birth and 12 days postnatal and the maximum tetanic force generated by the muscle increased by fourfold. Removal of nerve L4 at birth did not alter the increase in fibre number and there was no difference between the tension generated by the l.g. muscle in the ipsilateral and contralateral limbs of operated animals. 4. The number of detectable motor units in a extracellular calcium concentration [( Ca]o) of 2 mM remained constant in L4 at about fifteen between birth and 12 days postnatal; the number of detectable motor units in L5 declined over this period from about fifteen to six in a [Ca]o of 2 mM. Following the removal of L4 at birth, the number of motor units in L5 increased to twenty by 3 days postnatal and remained there for at least 12 days in a [Ca]o of 2 mM. 5. The mean size of motor units and the range of motor unit sizes declined for both L4 and L5 during the postnatal period. Following the removal of L4, the mean size of motor units and the range of motor unit sizes in L5 failed to decline. 6. The number of motor units detected at birth in a raised [Ca]o of 3-5 mM increased in L4 and L5 to about twenty; this estimate in high [Ca]o remained constant during the postnatal period. Estimates of the size of the large, low threshold motor units declined whether these were made in low or high [Ca]o.(ABSTRACT TRUNCATED AT 400 WORDS)

Proton NMR of aequorin. Structural changes concomitant with calcium-independent light emission

Aequorin, a Ca(II)-sensitive bioluminescent protein from jellyfish, emits light at 469 nm from an excited state of a substituted pyrazine (oxyluciferin) which results from the oxidation of a chromophore molecule that is noncovalently bound to the protein. The chromophore is oxidized when Ca(II) or other activating metal ions are bound by aequorin. In the absence of Ca(II), spontaneous emission of light, referred to as Ca(II)-independent light emission, occurs at a rate less than 10(-6) of that for Ca(II)-induced emission. Proton nuclear magnetic resonance (NMR), circular dichroism (CD), and fluorescence were used to study structural changes of aequorin accompanying Ca(II)-independent light emission. Time course studies by 1H NMR and CD demonstrate that as a result of Ca(II)-independent light emission, aequorin progressively changes from a rigid, fully active form showing little segmental mobility to a practically unfolded, discharged (i.e., inactive) form in which a number of amino acid residues are significantly mobile. This slow discharged protein (SDP) is distinct in nature and conformation from aequorin which has been discharged by Ca(II), i.e., the blue fluorescent protein. The rate of Ca(II)-independent discharge of aequorin is substantially reduced in the presence of excess Mg(II); the time constant for inactivation at 5 degrees C is 30 days with no Mg(II) present and 70 days with Mg(II) present. The NMR spectra are nearly identical at a given stage of inactivation whether or not Mg(II) is present. Oxyluciferin remains bound to SDP. If it is removed, however, by column chromatography, the resulting apo-SDP partially refolds, and the segmental mobility acquired in the formation of SDP is significantly attenuated particularly for some of the aromatic amino acid residues.

Increase of plasma renin activity after subcutaneous application of compound 48/80 in the rat

Subcutaneous (s.c.) administration of compound 48/80 (3.0 mg/kg) to conscious rats produced a time-dependent long-lasting increase of plasma renin activity (PRA). A dose-related increase of the hematocrit was also observed after injection of compound 48/80. The onset of the hematocrit increase preceded that of PRA increase. Pretreatment with a dose of more than 20 mg/kg of histamine H1-receptor antagonists such as tripelennamine or diphenhydramine prior to the injection of compound 48/80 (3.0 mg/kg s.c.) attenuated or abolished the effects of compound 48/80 on PRA, hematocrit and plasma extravasation. Pretreatment with cimetidine (histamine H2-receptor antagonist, 40 mg/kg i.p.) had no effect on these plasma variables. The increase of PRA caused by s.c. administration of compound 48/80 was not affected by the pretreatment with propranolol (beta-adrenoceptor antagonist, 10 mg/kg i.p.), which completely inhibited the isoproterenol (0.5 mg/kg s.c.)-induced PRA increase. Administration of compound 48/80 did not induce a significant PRA increase in the nephrectomized rats although the increase of hematocrit following s.c. administration of compound 48/80 persisted despite the absence of kidneys. S.c. administration of compound 48/80 (3.0 mg/kg) led to a significant decrease of histamine content at the site of injection and to a significant increase in plasma histamine concentration without affecting arterial blood pressure. The present data suggest that s.c. administration of compound 48/80 stimulates the release of histamine from cutaneous mast cells, which cause an increase in vascular permeability to plasma protein via the stimulation of histamine H1-receptors, then leads to hypovolemia. The resulting hypovolemia may directly stimulate the juxtraglomerular cells of the kidney to release renin.

Whole bowel irrigation--an alternative to traditional bowel washout

The objective of this study was to determine whether or not whole bowel irrigation through oral route was a safe and acceptable alternative to traditional bowel washout per rectum in preparation for large bowel surgery. Out of a total of 114 patients, 32 had whole bowel irrigation, 71 had traditional washout and 11 had no bowel preparation. The irrigation involved approximately 12 litres of normal saline over an average period of 3 1/4 hours. The preparation of the colon by whole bowel irrigation was better as indicated by total absence of faeces and the cleanliness of the colon at operation. However, there was no significant difference in wound infection rate between the two groups although the severity of wound infection was lesser in the first group. There were no major complications like anastomotic breakdown, burst abdomen, abscess or fistula formation and septicaemia in this group. Based on this experience we believe that whole bowel irrigation is a good alternative method of bowel preparation. The advantages of this method are that it is short and rapid, avoiding prolonged pre-operative hospitalisation and is acceptable to most patients.

Ca2+ regulation of tight-junction permeability and structure in Necturus gallbladder

To explore the role of Ca2+ in tight-junction permeability, the Necturus gallbladder was exposed to varying Ca2+ concentrations and to the Ca2+ ionophore A23187 added to the mucosal side (1.9 X 10(-6) to 6.8 X 10(-5) M). Electrophysiological parameters measured in an Ussing-type chamber were correlated with tight-junction morphology revealed by freeze-fracture electron microscopy. In Ca2+-free bathing media, transepithelial resistance decreases and tight-junctional ultrastructure is fragmented. In 1.8 mM Ca2+ media, A23187 induces an initial drop in transepithelial resistance, followed by an increase in transepithelial resistance to a value 20% above base line. At peak response to A23187, NaCl diffusion potentials decrease. Freeze-fracture replicas reveal that the number of junctional strands increase pari passu with junctional depth. Both physiological and morphological changes were partially reversible. The initial decrease in transepithelial resistance coincided with a persistent hyperpolarization of the mucosal cell membrane potential difference and a decrease in the mucosal-to-serosal cell membrane resistance ratio. Thus A23187 alters both the transcellular and paracellular pathway, resulting in opposing effects on transepithelial resistance.

Fracture studies on a mammalian semicircular canal

In the present work the pressures necessary to fracture the semicircular canal of the mammalian inner ear, specifically the squirrel monkey, have been investigated experimentally. The results indicate that individual canals can fracture when subjected to internal pressures of approximately 1.6 +/- 0.4 MPa. Simulation testing using Plexiglas and polycarbonate specimens, to represent the location of a possible osteoclast site within the bone forming a semicircular canal, demonstrates further that fracture of the canal can be initiated at this or even lower pressures when the pressure is generated within a simulated osteoclast site. These results provide useful information for a better understanding of the mechanisms by which bubble nucleation and growth could cause pressures of this magnitude within an osteoclast cavity during the decompression phase of a diving schedule.

Intraspecies variation in methacholine-stimulated esterase release from mouse submandibular gland

Esterase release was investigated in male and female submandibular glands of 5 strains of mice (ICR/BR, ND/4BR, SW/BR, DDS/Cox and C57BL/6BR) using dispersed cells prepared by treatment with collagenase and hyaluronidase. The muscarinic-cholinergic agonist methacholine stimulated esterase release in C57BL/6BR, DDS/Cox and SW/BR females and DDS/Cox males in a dose-dependent manner, but did not stimulate esterase release in ICR/BR and ND/4BR strains of both sexes. The percentage release of esterase over control in response to methacholine in females was of the descending order: C57BL/6BR, DDS/Cox, SW/BR, ND/4BR, ICR/BR. There was a close relationship between the percentage release of esterase by methacholine and the esterase activity in homogenate of submandibular gland. The lower the esterase content in the homogenate of mouse submandibular gland, the higher the percentage release of esterase by methacholine stimulation in the dispersed cells.

Cytoplasmic regulation of tight-junction permeability: effect of plant cytokinins

The significance of the "leaky" tight junction might be understood better if cells of the epithelial monolayer possessed mechanisms to regulate molecular flow through the junction. To test this possibility, Necturus gallbladder, a representative leaky epithelium, was studied before, during, and after mucosal exposure to plant cytokinins and two other microfilament-active drugs, cytochalasin B and phalloidin. Concomitant with morphological changes in microfilaments, cytokinins induced rapid reversible increases in transepithelial resistance and potential difference (PD) and decreases in NaCl dilution potentials, with no change in the ratio of relative cell membrane resistances. Cytochalasin B (0.2-1.2 microM) and phalloidin (0.6-12.7 microM) caused similar changes in transepithelial resistance and PD. When the intramembranous structure of tight junctions was studied by freeze fracture, peak cytokinin-induced increments in transepithelial resistance were associated with more disorder in the strand meshwork resulting in a small increase in tight junction depth, but there was no evidence of de novo strand assembly. These studies suggest that permeability of the tight junction of Necturus gallbladder is subject to rapid reversible modulation, possibly under cytoskeletal control.

The effects of pentobarbitone and urethane on pulmonary airway resistance in guinea-pigs and their interactions with drugs

1 Propranolol increased pulmonary airway resistance (PAR) in the conscious guinea-pig, whereas atropine had no effect, suggesting the existence of a continual sympathetic bronchodilator tone. 2 The direct bronchoconstrictor effects of histamine, acetylcholine and 5-hydroxytryptamine were modified by autonomic reflexes: a bronchodilator one, abolished by propranolol, and a cholinergic bronchoconstrictor one, seen with histamine. 3 Pentobarbitone increased PAR, an effect which was reduced by propranolol but which was unaffected by atropine. The bronchoconstrictor effects of histamine, acetylcholine and 5-hydroxytryptamine were potentiated by pentobarbitone. 4 Pentobarbitone therefore appears to inhibit the adrenergic bronchodilator tone and to depress adrenergic reflexes, these being the preponderant autonomic influences in these experiments. 5 Like pentobarbitone, urethane increased PAR in the conscious guinea-pig and potentiated the bronchoconstrictor effects of the three amines. These actions are similarly attributed to a reduction in adrenergic influences.