Isolation of myocardial L-type calcium channel gating currents with the spider toxin omega-Aga-IIIA

The peptide omega-agatoxin-IIIA (omega-Aga-IIIA) blocks ionic current through L-type Ca channels in guinea pig atrial cells without affecting the associated gating currents. omega-Aga-IIIA permits the study of L-type Ca channel ionic and gating currents under nearly identical ionic conditions. Under conditions that isolate L-type Ca channel currents, omega-Aga-IIIA blocks all ionic current during a test pulse and after repolarization. This block reveals intramembrane charge movements of equal magnitude and opposite sign at the beginning of the pulse (Q(on)) and after repolarization (Q(off)). Q(on) and Q(off) are suppressed by 1 microM felodipine, saturate with increasing test potential, and are insensitive to Cd. The decay of the transient current associated with Q(on) is composed of fast and slow exponential components. The slow component has a time constant similar to that for activation of L-type Ca channel ionic current, over a broad voltage range. The current associated with Q(off) decays monoexponentially and more slowly than ionic current. Similar charge movements are found in guinea pig tracheal myocytes, which lack Na channels and T-type Ca channels. The kinetic and pharmacological properties of Q(on) and Q(off) indicate that they reflect gating currents associated with L-type Ca channels. omega-Aga-IIIA has no effect on gating currents when ionic current is eliminated by stepping to the reversal potential for Ca or by Cd block. Gating currents constitute a significant component of total current when physiological concentrations of Ca are present and they obscure the activation and deactivation of L-type Ca channels. By using omega-Aga-IIIA, we resolve the entire time course of L-type Ca channel ionic and gating currents. We also show that L- and T-type Ca channel ionic currents can be accurately quantified by tail current analysis once gating currents are taken into account.

Effects of 'stroke-belt' residence, screening blood pressure and personal history risk factors on all-cause mortality among hypertensive veterans

OBJECTIVES

To seek regional differences within the USA in the 'all-cause mortality' of hypertensive men during the 14 years following institution of antihypertensive treatment, and to determine how other pretreatment data can be related to that all-cause mortality.

DESIGN

In the mid-1970s pretreatment clinical data were collected and computerized for 5698 hypertensive veterans. Deaths during the subsequent 14 years were obtained from the Veterans Administration Beneficiary Identification and Record Location System and the National Death Index. Relationships between pretreatment data and death were sought using chi 2- and z-tests for bivariate comparisons and logistic regression for multivariate analyses.

PATIENTS

Half of the 5698 previously untreated male hypertensive military veterans were Black. Their mean age was 52.3 years and mean pretreatment blood pressure was 160/104 mmHg. Additional pretreatment data included body mass index, cigarette and alcohol usage, age and self-reported comorbidities. These patients began antihypertensive treatment during 1974-1975 in 28 special Veterans Administration outpatient clinics throughout the USA.

RESULTS

During the 14 years after treatment began, 2283 of these patients (40%) died. Those from the southeastern USA, i.e. in the 'Stroke Belt', were 1.32-fold more likely to die than patients living elsewhere. Other pretreatment characteristics positively related to all-cause mortality included age, systolic blood pressure, cigarette and alcohol usage, and self-reported comorbidities. Race was unrelated to mortality.

CONCLUSION

All-cause mortality was increased among hypertensive subjects from the southeastern USA. The reasons for this excess mortality remain unclear. Other pretreatment characteristics were also related to mortality, but race was not.

Excess fruit juice consumption as a contributing factor in nonorganic failure to thrive

OBJECTIVE

To determine whether excessive consumption of fruit juice is a contributing factor in nonorganic failure to thrive in early childhood.

METHODS

Eight patients, aged 14 to 27 months, referred for failure to thrive were evaluated by medical history, physical examination, and biochemical assessment. Growth patterns were reviewed and anthropometric measurements including skinfold thickness and midarm circumference were obtained. Diet history included 3-day food records and 24-hour diet recalls. An open-ended interview explored factors associated with fruit juice consumption. Breath hydrogen testing of fructose, sorbitol, or fruit juice was performed in three children who had a history of diarrhea or gastrointestinal complaints. Nutritional intervention focused on reducing fruit juice consumption and increasing the energy and nutrient density of the children's diets.

RESULTS

In each case, deterioration of weight and linear growth progression coincided with excessive juice consumption. All children exhibited weights < 5th percentile and five also had lengths < -5th percentile. Weight-for-length deficits ranged from 11% to 25%. Two patients demonstrated low arm muscle mass and five children had diminished fat stores. Organic disease was ruled out in all cases. Three children had iron deficiency. The children's diets were hypocaloric, providing 78% to 92% of recommended energy intake for age and weight. Dietary intake included considerable juice consumption (12 to 30 oz/d). Fruit juice, primarily apple juice, contributed 25% to 60% of daily energy intake. As a result, food consumption was reduced; lowering dietary protein, fat, and micronutrient intakes. Excessive juice was consumed for various reasons including children's preferences, parental health beliefs, behavioral feeding difficulties, and financial considerations. Breath hydrogen testing revealed malabsorption of fructose and/or sorbitol. After nutritional intervention, dietary intake increased to 96% to 116% of recommended intakes. Weight gain increased significantly in the first month and persisted for follow-up of 5 to 18 months.

CONCLUSIONS

These findings indicate that large intakes of fruit juices may displace more calorie- and nutrient-dense foods. Additionally, fructose and sorbitol malabsorption may occur. Excess fruit juice consumption may present a contributing factor in nonorganic failure to thrive.

Body composition and spontaneous growth hormone secretion in normal short stature children

This study was designed to compare the relationship of measured and estimated indices of adiposity with the spontaneous GH secretion (SGHS) in 37 normal short stature children. Fifteen of the 37 patients (10 males and 5 females) were pubertal, and 22 (17 males and 5 females) were prepubertal. All patients underwent a review of their medical history, a physical exam, laboratory tests, and a nutritional assessment that included anthropometry and evaluation of body composition by bioelectric impedance. The percentage of body fat and body fat mass index were used as measured indices of adiposity. The weight for height ratio, body mass index, and body mass index z-scores were calculated and used as estimated indices of adiposity. Our results showed that SGHS is greatly influenced by variations in adiposity in normal short stature children, and measured indices of adiposity demonstrated the strongest negative correlation with SGHS. Gender differences were apparent in the degree of adiposity that modified SGHS, and it appears that adiposity altered the amplitude of GH pulses in pubertal patients and the number of pulses in prepubertal children. These results suggest that interpretation of SGHS must take into account body composition and gender in addition to pubertal status.

The effects of orally administered calcium pentosan polysulfate on inflammation and cartilage degradation produced in rabbit joints by intraarticular injection of a hyaluronate-polylysine complex

OBJECTIVE

To determine the antiinflammatory and cartilage-protecting activities of orally administered calcium pentosan polysulfate (CaPPS) in a rabbit model of inflammatory arthritis.

METHODS

A single intraarticular injection of a preformed polycation complex (PC) of poly-D-lysine and hyaluronan was used to induce joint inflammation; saline was injected into the contralateral joint as a control. Animals were killed 1, 4, 7, or 10 days post-PC injection. CaPPS, at 5 mg/kg, 10 mg/kg, or 75 mg/kg, was given every 48 hours commencing 7 days prior to PC injection. Serum interleukin-6 (IL-6), synovial fluid (SF) prostaglandin E2, cell numbers, and cartilage proteoglycan (PG) content, composition, and biosynthesis were determined for PC- and saline-injected joints.

RESULTS

In PC-injected, non-drug-treated animals, serum IL-6 activity, SF leukocyte numbers, and prostaglandin E2 levels were elevated, while cartilage PG content and biosynthesis were reduced. CaPPS at 10 mg/kg, but not at 5 mg/kg, decreased serum IL-6 levels but maintained cartilage PG concentration and biosynthesis. However, SF leukocyte counts and prostaglandin E2 levels (except on day 1) were not reduced.

CONCLUSION

The ability of CaPPS to attenuate serum IL-6 levels and preserve cartilage PGs in inflamed rabbit joints suggests that this substance could be of value as an effective orally administered chondroprotective, antiarthritic drug.

Speech by any other name: the role of communication aids in interaction

The functional communication systems of four physically disabled children with severe speech impairment were evaluated in terms of: (1) perceived dominant modes of communication; (2) observed frequency of communication mode occurrence; and (3) role of communication device in total communication system. All four subjects used a range of communication modes to reflect personal and listener preferences, and in response to differing conversational requirements. 'Standard' communication modes were mentioned more frequently by teachers and parents, and were observed more frequently in interactions. Augmentative and alternative communication devices played a limited but important role within total communication systems. A hierarchy of influences affecting the choice of communication mode is suggested.

Endoscopic diagnosis of chronic hypertrophic pyloric gastropathy in dogs

The endoscopic appearance of chronic hypertrophic pyloric gastropathy (CHPG) in five dogs is described. Several patterns of enlarged mucosal folds that surrounded and obstructed the pyloric canal were observed. Initially, endoscopically obtained biopsy samples of mucosa were judged to be histologically normal. Diagnosis of CHPG was confirmed and relief of pyloric obstruction accomplished at exploratory laparotomy (in four dogs). Retrospective evaluation of pyloric tissue samples, obtained during endoscopy, identified subtle histological characteristics of CHPG. Gastric and duodenal neoplasia or antral polyps can mimic the endoscopic appearance of CHPG but can be differentiated based on their endoscopic and histological appearance. These cases show that endoscopic examination is a valuable procedure for the diagnosis of CHPG in dogs that chronically vomit.

Nutrition in adolescence

Adolescence is often considered a nutritionally vulnerable period because of its characteristic rapid physical and psychological changes. Nutritional risks for both undernutrition and overnutrition are present and may be increased during physiologic stress such as athletics and pregnancy. Appropriate nutrition is important for maintaining optimal health and normal growth and development, as well as for preventing future chronic disease.

Platysma myocutaneous flap for head and neck reconstruction in cats

Squamous cell carcinoma is the fourth most common neoplasm in cats. As in man, local resective surgery of stage III and IV carcinoma often results in recurrence related to compromised margins. Radical resective procedures may be performed when reconstructive techniques are available to restore cosmesis and function. A platysma myocutaneous flap that was based on a cutaneous branch of the caudal auricular artery and vein was developed to fulfill this requirement. Control flaps, which included ligation and division of the caudal auricular artery and vein, were similarly developed on the contralateral aspect of the neck. Mean survival of all platysma myocutaneous flaps (86.7%), compared with control flaps (62.9%), was significantly different (p < .05). Flaps grouped in lengths of 6, 9, and 12 cm had mean survival lengths of 93.8%, 81.9%, and 84.4%, respectively. The mean survival length of flaps measuring 12 cm in length was significantly different (p < .05) compared with flaps measuring 6 and 9 cm. On the basis of the results of this study, the platysma myocutaneous flap based on a cutaneous branch of the caudal auricular artery and vein may be a source of tissue for reconstructive procedures of the head and neck in cats.

Evaluation of bending strength of five interdental fixation apparatuses applied to canine mandibles

Strength in bending was determined for interdental fixation apparatuses applied to hemimandibles obtained from 24 canine cadavers. Hemimandibles were osteotomized perpendicular to the long axis between the third and fourth premolars, and segments were stabilized with 1 of 5 interdental fixation apparatuses: Erich arch bar (EAB, n = 6); Stout loop (SL, n = 6); acrylic (A, n = 6); Stout loop and acrylic (SLA, n = 24); and Erich arch bar and acrylic (EABA, n = 6). Ultimate strengths (mean +/- SEM) of EAB, SL, A, SLA, and EABA were 395 +/- 48; 523 +/- 57; 1,106 +/- 102; 1,306 +/- 156; and 2,707 +/- 504 N.m, respectively. Stiffness (mean +/- SEM) of EAB, SL, A, SLA, and EABA were 2,944 +/- 357; 6,322 +/- 2,201; 16,010 +/- 5,017; 15,777 +/- 1,026; and 27,079 +/- 5,576 N.m/radian, respectively. Yield strengths (mean +/- SEM) of EAB, SL, A, SLA, and EABA were 66 +/- 6; 264 +/- 19; 911 +/- 126; 1,114 +/- 159; and 1,855 +/- 401 N.m, respectively. There were no significant differences in acrylic weight, cross-sectional area of the acrylic, or area moment of inertia of acrylic at the osteotomy site among A, SLA, and EABA; and there were no significant differences in osteotomy surface area and area moment of inertia at the osteotomy site among all apparatuses (P > 0.05). The EABA apparatus had significantly higher mean ultimate strength, mean stiffness, and mean yield strength compared to other interdental fixation apparatuses. There were no significant differences in the mean ultimate strength, mean stiffness, or mean yield strength between EAB and SL (P > 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Ultrastructure of human melanosis coli with reference to its pathogenesis

Colonic mucosal biopsies from patients with melanosis coli were examined by electron microscopy. They showed apoptosis of colonic surface epithelial cells and phagocytosis of resulting apoptotic bodies by intraepithelial macrophages. The latter migrated to the lamina propria where intracellular degradation of the apoptotic bodies resulted in formation of lipofuscin, characteristic of this condition. The results showed the pathogenesis of human melanosis coli was identical to that determined in an animal model of this disease.

Evaluation of the caudoventral portion of the mandible as a donor site for corticocancellous bone for periodontal surgery in dogs

Corticocancellous bone graft was obtained from the caudoventral portion of the mandible of 8 dogs. The recipient site was an alveolar jugal and alveolar defect from vital root amputation of the mesiobuccal root of the maxillary fourth premolar. Anatomic observations of 20 canine cadavers indicated that guidelines for harvesting bone from the caudoventral portion of the mandible of dogs were the mesial aspect of the masseteric fossa, the distal aspect of the roots of the first mandibular molar, and the ventral aspect of the mandibular canal. The mean weight of corticocancellous bone harvested was 0.4 +/- 0.1 g. Harvested corticocancellous bone was adequate to fill recipient sites measuring a mean volume of 105.0 +/- 28.5 mm3. Histologic evaluation of the recipient site revealed progressive osseous integration of the bone-graft site during a mean follow-up period of 3.5 +/- 1.9 months. There was normal bone healing of the donor site without adverse effects on the mandibular molars or neurovascular structures of the mandibular canal. Vital amputation sites receiving silver amalgam had evidence of plasmacytic/lymphocytic inflammation associated with residual silver amalgam in the bone-graft area. The caudoventral portion of the mandible may be used as a donor site for autogenous corticocancellous bone in periodontal surgery of dogs.

Nucleosome structural changes during derepression of silent mating-type loci in yeast

Mutant a and alpha yeast cells were created with histone H3 containing cysteine in place of alanine 110. Because transcriptionally active nucleosomes "unfold" to reveal the histone H3-thiol groups at the center of the core, the active nucleosomes of the mutant strain can be isolated by mercury-affinity chromatography. We compared the unbound and mercury-bound nucleosomes of haploid H3-mutant strains expressing either the MAT alpha or the MATa mating-type locus. In a MAT alpha strain, the Hg-bound nucleosomes are enriched in MAT alpha DNA but lack the DNA of the transcriptionally silent HMRa mating-type locus. Conversely, in a MATa strain, the Hg-bound nucleosomes are enriched in MATa DNA sequences but deficient in HML alpha DNA. When the SIR3 gene, known to be required for silencing of the repressed mating-type loci, is mutated in the MAT alpha strain, transcription of the HMRa ensues, and its nucleosomes, as well as those of the MAT alpha locus, are retained by the organomercurial column. It follows that derepression of the silent mating-type locus, caused by the sir3 null mutation, is accompanied by an unfolding of its nucleosomes to reveal the histone H3 SH groups at their centers. Nucleosomes of the pheromone-encoding gene MFA2, a gene that is expressed in MATa cells but not in MAT alpha cells, are bound to the organomercurial column when isolated from MATa cells but not from MAT alpha cells. Thus, there is a good correlation between nucleosome unfolding and the renewed transcriptional activity at mating-type loci, and at MFA2, which had been silenced for prolonged periods. A close temporal correlation between nucleosome refolding and the cessation of transcription is not always observed in yeast, however, in contrast to observations in mammalian cells. For example, nucleosomes of the GAL1 gene are maintained in a "poised" or "primed" thiol-reactive state even when the gene is not being transcribed (Chen, T. A., Smith, M. M., Le, S., Sternglanz, R., and Allfrey, V. G. (1991) J. Biol. Chem. 266, 6489-6498). It follows that the unfolding of the nucleosome cores of the yeast H3 mutant is regulated by factors that are not temporally linked to the recruitment or traverse of the RNA polymerase complex, but which may determine the rate at which different domains of chromatin adapt to the need for transcription of the associated DNA sequences.

High affinity block of myocardial L-type calcium channels by the spider toxin omega-Aga-toxin IIIA: advantages over 1,4-dihydropyridines

The peptide omega-agatoxin IIIA (omega-Aga-IIIA) from venom of the funnel web spider Agelenopsis aperta blocks L-type Ca2+ channels in neurons and myocardial cells with high affinity. We report that omega-Aga-IIIA also blocks whole-cell Ca2+ channel currents in guinea pig atrial myocytes. Although other high affinity blockers of L-type Ca2+ channels are available (such as the 1,4-dihydropyridines), omega-Aga-IIIA is a valuable pharmacological tool; omega-Aga-IIIA is the only known ligand that blocks L-type Ca2+ channels with high affinity at all voltages (IC50 approximately 1 nM) and it causes little or no block of T-type Ca2+ channels, unlike the 1,4-dihydropyridines. We use omega-Aga-IIIA to selectively eliminate L-type Ca2+ currents and we show that felodipine blocks T-type Ca2+ currents. Consequently, the toxin is better than dihydropyridines for separating ionic currents through voltage-dependent Ca2+ channels and defining their physiological function.

Histone H3 transcription in Saccharomyces cerevisiae is controlled by multiple cell cycle activation sites and a constitutive negative regulatory element

The promoters of the Saccharomyces cerevisiae histone H3 and H4 genes were examined for cis-acting DNA sequence elements regulating transcription and cell division cycle control. Deletion and linker disruption mutations identified two classes of regulatory elements: multiple cell cycle activation (CCA) sites and a negative regulatory site (NRS). Duplicate 19-bp CCA sites are present in both the copy I and copy II histone H3-H4 promoters arranged as inverted repeats separated by 45 and 68 bp. The CCA sites are both necessary and sufficient to activate transcription under cell division cycle control. A single CCA site provides cell cycle control but is a weak transcriptional activator, while an inverted repeat comprising two CCA sites provides both strong transcriptional activation and cell division cycle control. The NRS was identified in the copy I histone H3-H4 promoter. Deletion or disruption of the NRS increased the level of the histone H3 promoter activity but did not alter the cell division cycle periodicity of transcription. When the CCA sites were deleted from the histone promoter, the NRS element was unable to confer cell division cycle control on the remaining basal level of transcription. When the NRS element was inserted into the promoter of a foreign reporter gene, transcription was constitutively repressed and did not acquire cell cycle regulation.

Problems in deterrence: a comparison of the driving histories of DUII and non-DUII drivers

Driving records of subjects arrested for driving under the influence of intoxicants (DUII), both recidivists and nonrecidivists, were compared with records of an age- and sex-matched random sample of non-DUII drivers. Major differences were found between DUII and non-DUII groups in the incidence of traffic violations but some differences also existed between nonrecidivist and recidivist DUII subjects. Rehabilitative diversion programs for first-time DUII offenders did not affect recidivism rates in the study population. Findings in this study suggest that general deterrence directed at the non-DUII population should receive emphasis equal to specific deterrence directed at DUII offenders.

Evaluation of the proximal portion of the femur as an autogenous cancellous bone donor site in dogs

The proximal portion of the femur was evaluated as a source of autogenous cancellous bone in dogs. Bilateral oval cortical defects were created in the lateral subtrochanteric area of the femur in 16 dogs. Cancellous bone was removed and the weight recorded. Cancellous bone was similarly harvested from the proximal portion of the humerus in 7 of these dogs. Subtrochanteric femoral defects in 11 dogs were randomly assigned to receive cancellous bone graft obtained from the femur (n = 4) or the humerus (n = 7). Subtrochanteric defects in 5 dogs were not grafted. Radiographic assessment of subtrochanteric defects was performed at 4-week intervals, and histologic assessment at 4, 8, 16, and 24 weeks after surgery. Nongrafted donor sites healed by ingrowth of trabecular bone during the first 12 weeks after surgery. By week 24, the lateral cortical wall had reformed, but remodeling was incomplete. Donor sites grafted with cancellous bone healed similarly, but with more rapid healing and more complete remodeling evident by week 24. Although the mean weight of cancellous bone harvested from the proximal portion of the femur (0.82 +/- 0.22 g) was significantly (P less than 0.05) less than that harvested from the proximal portion of the humerus (1.38 +/- 0.29 g), there was no qualitative histologic or radiographic difference in bony healing of grafted defects. We determined that the proximal portion of the femur can be safely used to provide moderate amounts of cancellous bone, and that a second bone graft can be collected from the same subtrochanteric donor site after 12 weeks.

Clinical evaluation of axial pattern skin flaps in dogs and cats: 19 cases (1981-1990)

Nineteen axial pattern skin flaps were used in 16 dogs and cats to provide skin for repair of extensive cutaneous defects. Retrospective evaluation of medical records was used to determine percentage flap survival, postoperative complications, and long-term outcome of axial pattern skin flaps. The most common indication for use of axial pattern flaps was to augment wound closure following tumor resection (n = 7). Other indications included trauma (n = 5), chronic nonhealing wounds (n = 4), urine-induced cellulitis (n = 1), idiopathic dermal necrosis (n = 1), and chronic lymphoplasmocytic dermatitis (n = 1). Mean flap survival (+/- SD) was 96% (+/- 8). Postoperative complications included wound drainage (n = 15), partial dehiscence of the sutured flap (n = 7), distal flap necrosis (n = 6), infection (n = 3), edema (n = 3), and seroma formation (n = 2). After a median follow-up time of 5 months, evaluation of animals indicated that surgery provided successful wound reconstruction with good cosmetic results. Reconstruction of large cutaneous defects is facilitated by axial pattern flap application regardless of cause of wound. Postoperative complications are common but amenable to standard wound management techniques such as drain placement and surgical debridement of devitalized distal flap skin.