Molecular basis for thermoprotection in Bemisia: structural differences between whitefly ketose reductase and other medium-chain dehydrogenases/reductases.

The silverleaf whitefly (Bemisia argentifolii, Bellows and Perring) accumulates sorbitol as a thermoprotectant in response to elevated temperature. Sorbitol synthesis in this insect is catalyzed by an unconventional ketose reductase (KR) that uses NADPH to reduce fructose. A cDNA encoding the NADPH-KR from adult B. argentifolii was cloned and sequenced to determine the primary structure of this enzyme. The cDNA encoded a protein of 352 amino acids with a calculated molecular mass of 38.2 kDa. The deduced amino acid sequence of the cDNA shared 60% identity with sheep NAD(+)-dependent sorbitol dehydrogenase (SDH). Residues in SDH involved in substrate binding were conserved in the whitefly NADPH-KR. An important structural difference between the whitefly NADPH-KR and NAD(+)-SDHs occurred in the nucleotide-binding site. The Asp residue that coordinates the adenosyl ribose hydroxyls in NAD(+)-dependent dehydrogenases (including NAD(+)-SDH), was replaced by an Ala in the whitefly NADPH-KR. The whitefly NADPH-KR also contained two neutral to Arg substitutions within four residues of the Asp to Ala substitution. Molecular modeling indicated that addition of the Arg residues and loss of the Asp decreased the electric potential of the adenosine ribose-binding pocket, creating an environment favorable for NADPH-binding. Because of the ability to use NADPH, the whitefly NADPH-KR synthesizes sorbitol under physiological conditions, unlike NAD(+)-SDHs, which function in sorbitol catabolism.

Effect of high temperature on the metabolic processes affecting sorbitol synthesis in the silverleaf whitefly, Bemisia argentifolii.

Whiteflies accumulate the polyhydric alcohol, sorbitol, when exposed to temperatures greater than about 30 degrees C. Feeding experiments using artificial diets containing labeled sucrose showed that more of the label was incorporated into whitefly bodies and less was excreted in the honeydew when feeding was conducted at 41 compared with 25 degrees C. Analysis of the components of the honeydew showed that more of the excreted label was in glucose and fructose and less in trehalulose at 41 degrees C than at 25 degrees C. A similar effect of temperature on honeydew composition occurred for whiteflies feeding on cotton leaves. Measurement of the activities of glycolytic, pentose-phosphate and polyol pathway enzymes at 30 and 42 degrees C showed that NADPH-dependent ketose reductase/sorbitol dehydrogenase (NADPH-KR/SDH), sucrase, glucokinase and glucose-6-phosphate dehydrogenase activities were stimulated to a greater extent at 42 degrees C than trehalulose synthase and fructokinase. NAD(+)-sorbitol dehydrogenase (NAD(+)-SDH) activity was inhibited at 42 degrees C. We propose that high temperature alters metabolic activity in a way that increases the availability of fructose and stimulates pentose-phosphate pathway activity, providing both the substrate and coenzyme for sorbitol synthesis. High temperature also increases the activity of NADPH-KR/SDH, the enzyme in whiteflies that synthesizes sorbitol, but inhibits the activity of NAD(+)-SDH, the enzyme that degrades sorbitol.

A thermoprotective role for sorbitol in the silverleaf whitefly, Bemisia argentifolii.

Accumulation of polyols in insects is well known as a cold-hardening response related to overwintering or to protection against cold shock. The silverleaf whitefly (Bemisia argentifolii, Bellows and Perring) is a major insect pest in tropical and subtropical regions where heat stress and desiccation pose formidable threats to survival. We found that sorbitol levels increased ten-fold when whiteflies were exposed to elevated temperatures. Sorbitol levels rose from 0.16nmolwhitefly(-1) at 25 degrees C to 1.59nmolwhitefly(-1) at 42 degrees C. Sorbitol levels fluctuated diurnally under glasshouse and field conditions increasing ten-fold from morning to early afternoon. Feeding experiments on artificial diets showed that both temperature and dietary sucrose concentration were key factors influencing sorbitol accumulation. Cell free extracts prepared from adult whiteflies catalyzed NADPH-dependent fructose reduction, but were unable to reduce glucose with either NADPH or NADH. Radiotracer experiments with labeled glucose and fructose showed that fructose was the immediate precursor of sorbitol. Thus, sorbitol synthesis in the whitefly is apparently unconventional, involving conversion of fructose by a novel NADPH-dependent ketose reductase. We propose that sorbitol accumulation is a mechanism for thermoprotection and osmoregulation in the silverleaf whitefly, allowing the insect to thrive in environments conducive to thermal and osmotic stress.

Changes in dental knowledge and self-efficacy scores following interventions to change oral hygiene behavior.

One hundred twenty-three male veterans were randomly assigned to control, education, and psychological groups to improve oral hygiene behavior. The educational group received four 40-min sessions designed to increase knowledge of the causes and prevention of dental disease. The psychological intervention also consisted of four 40-min sessions. However, a psychologist provided the intervention using a Stage of Change intervention. The control group received pre- and post-testing only. There were no significant changes in dental knowledge for the control group while the increases in dental knowledge in the educational and psychological groups were similar and statistically significant. Pre-Post change scores for flossing self-efficacy scores showed significant changes for all groups. The magnitude of changes was similar when the control and educational groups were compared. In contrast, the psychological intervention group demonstrated significantly greater flossing self-efficacy changes when compared to either the control or the educational groups. These results suggest that increases in self-efficacy may be an important component of interventions designed to change health behavior and may serve a role in evaluating and comparing the efficacy of these interventions.

Use of Dental Coping Beliefs Scale to measure cognitive changes following oral hygiene interventions.

This study employed a recently developed questionnaire, the Dental Coping Beliefs Scale (DCBS), to evaluate the effect of oral hygiene interventions on dental beliefs. The DCBS was administered to 100 subjects. Compared to an untreated control group, there was an increase in the ability to improve oral health through self-effort for the three experimental interventions: Attention (Al), Education (El) and Cognitive Behavioral (CBI). When the Dental Coping Beliefs Scale was divided into scales of Internal Locus of Control, External Locus of Control, Self-Efficacy, and Oral Health Beliefs, additional changes were evident. For the CBI Group, all four scales changed significantly between baseline measurement and post-intervention toward beliefs favoring control and prevention of dental disease using brushing and flossing. For the A and E groups, three scales paralleled the results of the CBI: Internal Locus of Control and Self-Efficacy increased and External Locus of Control decreased after the intervention. However, unlike the CBI, Oral Health Beliefs did not significantly change. Overall, for all experimental groups, there was a shift from external locus of control beliefs to internal beliefs. The untreated Control Group showed no changes across the five weeks. This study was supported by a VA Medical Research Service Merit Review Award.

Alveolar soft part sarcoma metastatic to the breast.

Metastasis to the breast is uncommon, with an incidence of 0.5-3%. Alveolar soft part sarcoma is rare, accounting for < 1% of malignant soft tissue tumors, which are themselves unusual. Excluding contralateral breast and hematologic malignant disease, the primary lesion in most cases of metastasis to the breast is melanoma, small cell carcinoma of the lung, or ovarian carcinoma, although rhabdomyosarcoma is the most common primary tumor in children. We describe a 26-year-old woman with no history of malignant disease who presented with two masses in the right breast that clinical evaluations and ultrasonography indicated were fibroadenomas. Pathological studies after excisional biopsy, however, indicated alveolar soft part sarcoma. Subsequent computed tomography showed the primary tumor in the anterior left thigh and multiple bilateral lung metastases. Because of the presence of distant metastases, the patient was treated with chemotherapy.

Localization of light-harvesting complex apoproteins in the chloroplast and cytoplasm during greening ofChlamydomonas reinhardtii at 38°C.

Assembly of the major light-harvesting complex (LHC II) and development of photosynthetic function were examined during the initial phase of thylakoid biogenesis inChlamydomonas reinhardtii cells at 38°C. Continuous monitoring of LHC II fluorescence showed that these processes were initiated immediately upon exposure of cells to light. However, mature-size apoproteins of LHC II (Lhcb) increased in amount in an alkali-soluble (non-membrane) fraction in parallel with the increase in the membrane fraction. Alkali-soluble Lhcb were not integrated into membranes when protein synthesis was inhibited, suggesting that they were not active intermediates in LHC II assembly, nor were they recovered in a purified chloroplast preparation. Immunocytochemical analysis of greening cells revealed Lhcb inside the chloroplast near the envelope and in clusters deeper in the organelle. Antibody binding also detected Lhcb in granules within vacuoles in the cytosol, and Lhcb were recovered in granules purified from greening cells. Our results suggest that the cytosolic granules serve as receptacles of Lhcb synthesized in excess of the amount that can be accommodated by thylakoid membrane formation within the plastid envelope.

Massive primary lipoma of the scrotum.

Most lipomas occurring in the scrotum originate and develop in the spermatic cord. In rare cases, however, lipomas originate in the fat cells of the subcutaneous tissues of the scrotal walls themselves. These primary lipomas of the scrotum vary in size. We describe a patient with a scrotal mass that, to our knowledge, is the largest scrotal lipoma originating in the tunica dartos reported in the English literature.

Decrease of polypeptides in the PS I antenna complex with increasing growth irradiance in the red alga Porphyridium cruentum.

Thylakoids isolated from cells of the red alga Porphyridium cruentum exhibit an increased PS I activity on a chlorophyll basis with increasing growth irradiance, even though the stoichiometry of Photosystems I and II in such cells shows little change (Cunningham et al. (1989) Plant Physiol 91: 1179-1187). PS I activity was 26% greater in thylakoids of cells acclimated at 280 µmol photons · m(-2) · s(-1) (VHL) than in cells acclimated at 10 µmol photons · m(-2) · s(-1) (LL), indicating a change in the light absorbance capacity of PS I. Upon isolating PS I holocomplexes from VHL cells it was found that they contained 132±9 Chl/P700 while those obtained from LL cells had 165±4 Chl/P700. Examination of the polypeptide composition of PS I holocomplexes on SDS-PAGE showed a notable decrease of three polypeptides (19.5, 21.0 and 22 kDa) in VHL-complexes relative to LL-complexes. These polypeptides belong to a novel LHC I complex, recently discovered in red algae (Wolfe et al. (1994a) Nature 367: 566-568), that lacks Chl b and includes at least six different polypeptides. We suggest that the decrease in PS I Chl antenna size observed with increasing irradiance is attributable to changes occurring in the LHC I-antenna complex. Evidence for a Chl-binding antenna complex associated with PS II core complexes is lacking at this point. LHC II-type polypeptides were not observed in functionally active PS II preparations (Wolfe et al. (1994b) Biochimica Biophysica Acta 1188: 357-366), nor did we detect polypeptides that showed immunocross-reactivity with LHC II specific antisera (made to Chlamydomonas and Euglena LHC II).

Metastatic breast carcinoma presenting as persistent diarrhea.

Patients with breast carcinoma metastatic to the colon generally present with multiple symptoms, usually pain, vomiting, nausea, and ascites. We describe a patient who presented only with persistent diarrhea, underwent surgery for colon cancer, and, on pathological evaluation of the surgical specimen, was found to have metastatic breast cancer affecting the colon. Metastatic breast cancer should therefore be suspected in patients with a history of breast cancer and diarrhea of unknown cause that is not accompanied by other symptoms. Evaluating such patients by colonoscopy and biopsy would provide important information relevant to choosing between colon surgery and systemic therapy.

Relationship of dental coping beliefs and oral hygiene.

Previous research has found varying relationships between dental beliefs and oral hygiene. In this study a recently developed questionnaire, the Dental Coping Beliefs Scale (DCBS), was used to study the relationship between plaque index and dental beliefs. The DCBS was administered to 99 subjects; at the same time, the standard of oral hygiene was determined by the use of the Plaque Index scoring system. The rating dentist had an established test-retest reliability of 0.91 in estimating plaque index. Correlations were obtained between each of the DCBS's 44 items and plaque index scores. Ten items were significantly correlated with plaque index, with r's from -0.19 (P less than 0.05) to -0.33 (P less than 0.001). The DCBS data was then analyzed by performing an oblique principal component cluster analysis to determine the major health belief composing the DCBS. Four clusters explained 38% of the total variance. The clusters were labeled Internal Locus of Control (15 items). External Locus of Control (15 items), Self Efficacy (8 items), and Oral Health Beliefs (6 items). Nine of the 10 items significantly correlated with plaque index were members of the External Locus of Control component. Thus, beliefs relating to increased external locus of control were related to higher plaque index.

The effect of a cognitive behavioral intervention on oral hygiene.

Several medical areas that require patient compliance have successfully used psychological interventions emphasizing cognitive behavioral components. However, there are no published reports on the effect of cognitive behavioral interventions on oral hygiene in adults using an experimental design. For this study, 100 male veterans age 21-65 years were randomly assigned to 4 groups (cognitive behavioral, education, attention control, and control); to compare the effectiveness of these interventions on oral hygiene, a 5-week pre-test-post-test design was utilized. The dependent variables were self-report of brushing and flossing behavior and dental plaque levels utilizing the plaque index. After the interventions, there was only one significant difference between the control and the experimental groups for brushing frequency. There were no significant differences among the experimental groups for this intervention. The self-report of flossing frequency significantly increased in all 3 treatment groups, but there were no significant differences between these groups. In addition, plaque levels decreased significantly in all 3 experimental groups. Plaque levels in the cognitive behavioral group were significantly lower than those of the educational group. It was not possible to determine whether the greater plaque reduction in the cognitive-behavioral group could be attributed to the nature of the intervention or to the extra time spent with patients in the cognitive behavioral group.

The retention of newly-acquired brushing and flossing skills.

Brushing and flossing ability increased dramatically 3 weeks following 2 sessions of oral hygiene instructions. At the same time, the plaque index for these patients decreased significantly. 1 year after the oral hygiene instruction, the plaque index for these patients returned to the pre-intervention levels. However, these patients were able to maintain their 3-week post-intervention brushing and flossing scores. We conclude that increased levels of plaque 1 year later, was not due to loss of brushing and flossing skills.

Cognitive-behavioral psychology and oral hygiene. A new perspective on an old problem.

This article describes the application of learning principles derived from behavioral and cognitive psychology to oral hygiene. It reviews the theoretical basis of a plaque prevention approach based on psychological models of self-control behavior. This approach was derived from research on learning environments, interviewing, behavior modification, and cognitive psychology.

Cognitive predictors of compliance in chronic disease patients.

Variables derived from the health locus of control construct and the Health Belief Model were used to predict compliance with medical regimen in chronically ill patients (adult-onset diabetics, hypertensives, and pulmonary disease patients). Stepwise multiple regression analyses were conducted with predictor variables: age, socioeconomic status, Internal Health Locus of Control (HLC), powerful others HLC, chance HLC, perceived severity of illness, outlook on illness, experienced symptoms, satisfaction with treatment, family support, and support of others. Dependent variables included three measures of compliance with medication regimen and two measures of compliance with self-management regimen. Patient satisfaction was a significant predictor of medication compliance, and lack of symptoms was most strongly associated with self-management compliance. Limitations of cognitive variables in predicting compliance in many chronic disease patients are discussed.