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Biomedical subjects

L White

Publications and source records attributed to L White.

At least 235 records · Page 13Linked to original sources
PubMed1983

Toothbrush pressures of orthodontic patients.

The intention of this study was to determine whether toothbrushing pressures varied significantly between groups of orthodontic patients who were good toothbrushers and those who were poor toothbrushers. Seventy-two patients undergoing full-banded orthodontic treatment were selected from the author's practice and were subjectively paired by him according to their habitual oral hygiene. One group of thirty-six patients who habitually displayed poor oral hygiene was compared to a group of thirty-six patients who habitually displayed good oral hygiene. A specially designed strain gauge with a force-averaging feedback mechanism was attached to each patient's manual toothbrush, and the force with which that patient brushed was averaged and recorded in pounds. The poor brushers averaged 0.20 pound, whereas the average pressure of the good brushers was 0.89 pound. The statistical evidence indicates that the difference between the two groups is highly significant and is unlikely to be due to chance alone. This study has shown that toothbrush pressures can be easily and accurately measured. The attempt to objectify a single characteristic of toothbrushing behavior in an orthodontic population is an effort to avoid the medical model explanation of behavior vis-a-vis the nonspecific and subjective word attitude. Future studies will determine whether poor toothbrushers can be changed into good toothbrushers through the progressive acquisition of greater toothbrushing forces.

Humans↗
PubMed1983

The role of chemotherapy in the treatment of retinoblastoma.

A review of the current status of chemotherapy in the treatment of retinoblastoma is presented. No consistently effective chemotherapeutic regimen for intraocular tumor has yet been discovered. An adjunctive role in the treatment of extraocular orbital disease has been suggested, but is unproven. Central nervous system involvement often responds to intrathecal chemotherapy. In cases diagnosed early, cure may be possible by the use of aggressive regimens including radiation therapy. Complete remissions are generally achieved in patients with systemic metastases. Cyclophosphamide is the most effective of the drugs used so far. However, relapses invariably follow, because effective maintenance chemotherapy has not yet been developed. Prevention of overt metastases by the use of adjuvant chemotherapy has recently been studied, but results remain inconclusive. Identification of reproducible prognostic criteria will enhance the design of future clinical studies. Laboratory research shows promise of more effective chemotherapeutic agents and combinations.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1983

Patterns of Hodgkin's disease at diagnosis in young children.

A retrospective analysis of 125 consecutive cases of Hodgkin's disease, seen at a pediatric institution, was conducted and 28 patients under the age of 7 years (young children) were selected for comparison with a control population, aged 7 or more years. Male to female ratios were: young children, 4.6:1 vs. 1.2:1 for the controls. Symptoms at diagnosis were present in 20% of patients under age 7 and in 42% of the others. Limited Hodgkin's disease (stages I and IIA) was found in 57% of young children and in 33% of the controls, while advanced disease (stages IIIB and IV) was diagnosed in 12% of young children and in 38% of the others. Histologic types differed as follows: the young group--lymphocyte predominance (LP) 21%, nodular sclerosis (NS) 50%, mixed cellularity (MC) 29%, and lymphocyte depletion (LD) 5%, vs. the controls--LP 5%, NS 73%, MC 17%, and LD 5%. Hodgkin's disease in the young child differs from that in older populations and appears to have a favorable distribution of prognostic criteria.

Adolescent↗
PubMed1982

Increased food intake following the manipulation of intracerebral dopamine levels with gamma-hydroxybutyrate.

The administration of gamma-hydroxybutyric acid (GHB) initially causes a temporary "sleep-like" state during which there is an increase in forebrain dopamine levels. The present series of experiments examined whether in the period following the GHB-induced behavioural depression, when accumulated dopamine is dispersed, there is any behavioural evidence of increased dopaminergic activity. The first experiment, in which GHB was injected directly into the cerebral ventricles, demonstrated that in the immediate post-recovery period rats exhibited various forms of stereotyped oral behaviour and stereotyped sniffing. Unexpectedly, it was also observed that if food were present animals preferred to eat. The nature of this feeding response was examined in two further experiments. Firstly, it was shown that in the period following the behavioural depression animals would perform, in a dose-dependent fashion, an operant response which was rewarded by food. Secondly, the GHB-induced increase in feeding was abolished by the pre-treatment of animals with either the dopamine synthesis inhibitor alpha-methyl-p-tyrosine, or the dopamine receptor blocker haloperidol. These data indicate that (i) in the period when it is known that the GHB-induced accumulation of dopamine is dispersing, there is behavioural evidence of increased dopaminergic activity; (ii) the feeding response is not a simple oral reflex; and (iii) in addition to being essential for food intake dopaminergic transmission may play a direct role in the production of feeding.

Amphetamine↗
PubMed1982

A syndrome of thrombosis and hemorrhage complicating L-asparaginase therapy for childhood acute lymphoblastic leukemia.

L-Asparaginase therapy for childhood acute lymphoblastic leukemia causes deficiencies of plasma hemostatic proteins, especially antithrombin, plasminogen, and fibrinogen. Severe thromboses and hemorrhages occurred in 18 children receiving vincristine, prednisone, and asparaginase therapy for ALL. Thirteen children had intracranial thrombosis or hemorrhage, four had extremity thrombosis, and one had both an intracranial hemorrhage and an extremity thrombosis. These events occur characteristically in the third and fourth weeks of therapy during or just after a three-week course of L-asparaginase. Symptoms of headache, obtundation, hemiparesis, and seizure were common for the intracranial events: local pain, swelling, and discoloration were common for the extremity thromboses. These complications have been recognized in 1 to 2% of children undergoing induction therapy which includes asparaginase.

Adolescent↗
PubMed1982

Effect of prolonged administration of interferon-alpha on pharmacokinetics, fever, lymphocyte proliferative response, and NK cell activity.

Over a 60-week period, a patient with multiple warts received a total of 281 x 10(6) units of human leukocyte interferon (IFN-alpha) by intramuscular (IM) or intralesional (IL) injections. Circulating IFN was significantly higher following IM administration than after IL administration. These pharmacokinetics did not change. The patient's body temperature was always significantly elevated after administration of IFN. However, hyporeactivity to the febrile response developed when the interval between repeated injections of IFN was less than six days. The lymphocyte count was significantly decreased within 5-7 h after administration of IFN and had returned to normal by 24 hours, whereas total WBC, platelet, and monocyte counts were not altered. There was a depression of specific lymphocyte proliferative response to herpes simplex virus after multiple daily injections, but not after prolonged therapy. Circulating natural killer (NK) levels were not elevated during the first two months of IFN therapy. After the patient had received about 100 x 10(6) units of IFN, however, the NK cell level became elevated and remained elevated upon cessation of treatment. NK activity was stimulated by in vitro incubation of peripheral mononuclear cells with 1000 units of IFN during the initial phase of treatment. A decline of in vitro stimulation of NK activity by interferon developed during two subsequent periods of treatment with mean daily doses of 2.46 and 1.07 x 10(6) units of IFN. Long-term therapy in our patient with an average of 4.7 x 10(6) units of IFN/week was well tolerated, did not irreversibly affect platelet or white cell counts or nonspecific or virus-specific cell mediated immune responses, and enhanced circulating NK levels.

Adult↗
PubMed1982

Genetic relatedness among human rotaviruses as determined by RNA hybridization.

Viral RNAs from human rotaviruses were compared by gel electrophoresis and by hybridization to probes prepared by in vitro transcription of two well-characterized laboratory strains (Wa and DS-1). Also, the viral RNAs were compared by hybridization to probes prepared from three of the test viruses. Thirteen specimens (diarrheal stools) were obtained from infants and children 5 to 21 months old on a single day at the emergency ward of the Caracas Children's Hospital, and an additional specimen was obtained from the same hospital 6 months before. When the electrophoresed viral RNAs were stained with ethidium bromide and examined by UV light, five different migration patterns (electropherotypes) were distinguished on the basis of differences in mobility of the RNA segments. The hybridization technique that was employed permitted only qualitative comparisons of corresponding genes of different human rotaviruses. Ten of the specimens contained enough virus to yield sufficient RNA for hybridization studies. Eight of the viruses studied by hybridization contained 4 to 11 genes that reacted specifically with the Wa probe to yield double-stranded RNA segments with a mobility similar to that of Wa viral RNA or test virus RNA. The other two viruses contained 11 genes that reacted specifically with the DS-1 hybridization probe to yield double-stranded RNA segments with a mobility similar to DS-1 viral RNA or test virus RNA. A more complex picture emerged when hybridization probes were prepared from three of the test viruses and used to compare the different electropherotypes. Corresponding genes that exhibited similar migration did not necessarily exhibit homology when studied by hybridization. Also, some corresponding genes that exhibited homology did not have the same mobility by gel electrophoresis.

Child, Preschool↗
PubMed1981

Hydroxyethyl starch for resuscitation of patients with hypovolemia and shock.

The authors evaluated the effectiveness of 6% hydroxyethyl starch (hetastarch) solution for treatment of hypovolemia in 46 critically ill patients. Thirty-two of the patients were studied retrospectively and in 14 patients, cardiopulmonary variables were prospectively measured. A total of 29 patients were in shock secondary to hypovolemia (13), sepsis (13), or myocardial infarction (3). Average hetastarch infusion volume was 829 and 842 ml, respectively, in prospectively and retrospectively studied patients, with maximum of 2000-2500 ml infused over 48 h. Approximately 30% of 24 h fluid needs were supplied with colloids. Infusion of 500 ml of hetastarch in 14 prospective study patients was associated with increases in pulmonary artery wedge pressure (WP) from 9 +/- 1.5 to 12 +/- 2.1 mm Hg, cardiac index (CI) from 2.9 +/- 0.2 to 3.5 +/- 0.3 (p less than 0.05) along with an increase in mean arterial pressure (MAP) from 87-99 mm Hg and reduction in arteriovenous O2 difference [C(a-v)O2] from 4.9 to 4.2 ml/dl. Intrapulmonary shunt (Qsp/Qt) was similar (20 vs. 21% as were alveolar-arterial O2 gradient [P(A-a)O2] (164 vs. 158 torr), whereas O2 consumption (VO2) increased from 224 to 247 ml/min. Immediate survival was 90% in shock patients and 100% in nonshock patients, whereas hospital survival was 65.5% and 88%, respectively. The authors conclude that hetastarch is an effective fluid for resuscitation of hypovolemic patients. This synthetic colloid does not appear to adversely affect pulmonary function.

Adolescent↗
PubMed1981

Virus detection by nucleic acid hybridization: examination of normal and ALS tissues for the presence of poliovirus.

A nucleic acid hybridization assay was developed as a sensitive assay for the presence of poliovirus RNA in human tissue. The assay could detect the presence of an average of one poliovirus per 200 cells. A method for determining the extent of degradation of the tissue RNA was developed and used to show that a significant fraction of human central nervous system (CNS) autopsy material contains highly degraded RNA which is unsuitable for hybridization studies. A total of 15 different control and amyotrophic lateral sclerosis tissues were assayed for the presence of poliovirus-like RNA. Virus RNA was detected in one of the control tissues and in none of the ALS tissues.

Amyotrophic Lateral Sclerosis↗
PubMed1981

An impossible dream?

Explore the source record for details and available documents.

American Nurses' Association↗
PubMed1981

Nonhormonal adrenocortical tumor in childhood: case report.

The case of a 4-year-old boy with a large, clinically nonhormonal adrenocortical tumor is presented. The tumor was judged to be malignant and treated with excision radiotherapy, and combination chemotherapy. At 47 months from diagnosis the patient remains free of disease. Review of the literature reveals the extreme rarity of such tumors in childhood. An abdominal mass is the usual presentation and the prognosis is very poor. The degree of malignancy is often difficult to determine but large tumors are more likely to metastasize.

Adrenal Cortex Neoplasms↗
PubMed1980

Role of erythropoietin and cyclic nucleotides in erythroid cell proliferation in fetal liver.

Cyclic AMP and cyclic GMP have been implicated as regulators of proliferation and differentiation in a variety of tissues including erythroid cells. Present studies indicate that erythropoietin is capable of stimulating an accumulation of cyclic GMP in fetal liver cultures. Erythropoietin (Ep) decreases the duration of the G1 phase of the cell cycle, diminishing the total cell cycle time by approximately 40%. In proliferating cells to which no Ep was added, concentrations of cyclic AMP and cyclic GMP changed as cells progressed through the cycle. Increases in cyclic GMP levels are associated with DNA synthesis and mitosis. On the other hand, cyclic AMP levels are associated with the G1 and G2 phases of the cycle. When Ep was included in cultures, the same cyclic nucleotide pattern relative to phases of the cell cycle was maintained. Thus, it is likely that cyclic GMP and cyclic AMP exert a regulatory influence on proliferation and differentiation of developing erythroid cells.

Animals↗