Near-infrared two-dimensional photonic band-gap materials

We describe the fabrication and optical transmission of two-dimensional periodic dielectric structures with photonic band gaps in the near infrared. The structures consist of triangular arrays of air cylinders embedded in a glass matrix, with center-to-center nearest-neighbor separations between 1.08 and 0.73 microm. The band gaps corresponding to the first Brillouin zone's boundaries occur at wavelengths between 2.5 and 1.1 microm. For each array size, the band gaps along the two high-symmetry propagation directions are spectrally overlapped for light polarized perpendicular to the cylinder axes. The observed positions, widths, and polarization dependence of the band gaps are in good agreement with theoretical calculations.

Palatal surgical splint for transverse stability of Le Fort I osteotomies: a technical note

A modified surgical splint for Le Fort I osteotomies with transverse expansion is presented. The splint is made of a transpalatal stainless steel bar with acrylic abutment against the palatal surface of the molar and bicuspid tooth. It is rigid and renders excellent retention. It causes minimal patient discomfort, and oral hygiene is hardly compromised.

Fibrodysplasia ossificans progressiva in two half-sisters: evidence for maternal mosaicism

Fibrodysplasia ossificans progressiva (FOP) is a rare autosomal dominant disorder of connective tissue characterized by congenital malformation of the great toes and by progressive heterotopic ossification of the soft tissues in specific anatomic and temporal patterns. We observed classic findings of FOP in 2 Native American half-sisters with the same unaffected mother and different unaffected fathers. This is the first report of FOP in sibs from different pregnancies with unaffected parents. The findings in this family indicate the possibility of maternal gonadal mosaicism in FOP and provide important new data for genetic counseling in this disease.

Primary extranodal CD3O-positive T-cell non-Hodgkins lymphoma of the oral mucosa. Report of two cases

CD3O-positive extranodal T-cell lymphomas predominantly occur in the skin, and they are characterized by a rather indolent course with spontaneous regression of individual lesions. Their occurrence in the oral mucosa is rare and not well documented. Two cases are reported, one occurring in the oral mucosa in a 61-year-old man and originally presenting as a multifocal eosinophilic ulcer of the mucous membrane, and the other one mimicking periodontitis, occurring in the maxillary gingiva of a 75-year-old woman.

Use of antibiotic-impregnated cement during hip and knee arthroplasty in the United States

A survey of practicing orthopaedists regarding their use of antibiotic(s) in bone-cement (ABC) was carried out. The initial sampling of 2,139 orthopaedists spanned the continental United States. Responses that passed fail-edit criteria were obtained from 1,015 physicians. Clinical practice patterns are highly variable. Adult reconstructive orthopaedic practitioners' belief in antibiotic(s) in bone-cement for the treatment of patients with previous sepsis is favorable. This opinion can be supported at the guideline level. Guidelines suggesting that liquid antibiotics should not be used as additions to polymethyl methacrylate are also supportable. The need for careful scientific inquiry and cost-effectiveness evaluation of the benefits and risks relating to the use of antibiotic additions to polymethyl methacrylate cement in joint arthroplasty exists. On the basis of such inquiry, educational dissemination to reduce practice variation would be indicated.

Double-blind, randomized trial of one versus three prophylactic doses of synthetic surfactant in 826 neonates weighing 700 to 1100 grams: effects on mortality rate. American Exosurf Neonatal Study Groups I and IIa

At 33 hospitals in the United States, a double-blind, randomized clinical trial was performed to compare one versus three prophylactic doses of synthetic surfactant in 700 to 1100 gm inborn infants. All 826 infants received an initial prophylactic dose of surfactant within 30 minutes of birth. Subsequently 410 infants received two doses of placebo (air) 12 and 24 hours later, and 416 infants received two additional doses of surfactant. By the age of 28 days, 70 infants who received one dose of surfactant and 40 infants who received three doses were dead, a 43% relative reduction in the mortality rate (30 fewer deaths; p = 0.002). By the age of 1 year after term, 87 infants who received one dose and 62 infants who received three doses were dead: a 29% relative reduction in the mortality rate (25 fewer deaths; p = 0.027). Infants who received three doses of surfactant required significantly less oxygen and less mean airway pressure for the first week of life. Necrotizing enterocolitis (9 vs 25 infants; p = 0.005), and use of high-frequency ventilation (13 vs 26 infants; p = 0.037); pancuronium (43 vs 62 infants; p = 0.045); and leukocyte transfusions (0 vs 4 infants; p = 0.042) were less frequent in the three-dose group, but air leak, bronchopulmonary dysplasia, intraventricular hemorrhage, patent ductus arteriosus, pulmonary hemorrhage, and infections were not different. These results indicate that physiologic findings, mortality rates, and probably morbidity rates are improved by two additional prophylactic doses of synthetic surfactant.

Efficacy of felbamate monotherapy in patients undergoing presurgical evaluation of partial seizures

The efficacy and safety of felbamate monotherapy were evaluated in 52 patients with refractory partial seizures with or without secondary generalization in a double-blind, randomized, placebo-controlled trial. Each patient completed a routine evaluation for epilepsy surgery and was randomized to receive either felbamate, titrated to a maximum daily dose of 3600 mg over 2 days, or placebo during the 10-day, inpatient, treatment phase. An intent-to-treat analysis was performed on the data of all 52 patients who received study medication, while a separate efficacy analysis also was performed on the data of 43 evaluable patients, which excluded protocol violators. The endpoint of the trial was completing 10 days of treatment or the occurrence of a fourth seizure. The primary efficacy variable was the average daily seizure frequency during the treatment phase for each patient. For the intent-to-treat analysis based on all 52 patients who received study medications, the mean rank of the daily seizure frequency for patients treated with felbamate was 21.6 compared to 29.6 for patients treated with placebo (P = 0.065). In the analysis based on the 43 evaluable patients, the mean rank of the daily seizure frequency for felbamate-treated patients was 17.0 compared to 25.4 for placebo-treated patients. This difference was statistically significant (P = 0.032) in favor of felbamate. Seizure frequency was decreased by 89.5% compared to baseline in nine patients who completed 10 days of felbamate therapy. This study permitted the rapid determination of the anticonvulsant activity of felbamate and demonstrated that felbamate is effective as monotherapy for the treatment of partial seizures.

Controlled-release drug delivery systems in cardiovascular medicine

Controlled-release drug delivery technology has had a significant effect on the pharmacotherapy of cardiovascular diseases. Oral and transcutaneous controlled-release systems allow relatively short-acting drugs to be administered once or twice daily with comparable therapeutic efficacy and fewer adverse reactions compared with standard formulations. They can provide decreased fluctuations in drug concentrations in plasma while possibly reducing the total amount of drug necessary for a clinical response. Techniques include the diffusion, bioerosion or degradation, and generation of osmotic pressure in orally active and transcutaneous drug delivery systems. Calcium-channel blocking agents, nitrates, beta-blocking agents, antiarrhythmic agents, clonidine, and nicotinic acid can be administered by these techniques, which have greatly influenced the application of these drugs in clinical practice.

Economic losses and decontamination

Mycotoxin contamination of crops may cause economic losses at all levels of food and feed production including crop and animal production, and crop distribution and processing. The national economy would be affected adversely by losses incurred by crop and livestock producers and the multiplier effect this has on other industries as a result of the reduced spending power of producers. Costs of chemical analyses, quality control and regulatory programs, research and development, extension services, law suits, and the cost of human illnesses must all be borne by the national economy. The value of the losses encountered depends on grain, animal, and animal product prices, interest rates, degree of contamination, and other economic variables. Even during favourable seasons it is likely that millions of dollars are lost as a result of the contamination of crops with mycotoxins. Many compounds and treatments have been tested in order to reduce mycotoxin concentrations in food and feed or to alleviate their adverse effects on animals. Some of these treatments show promising prospects for commercial application, while others have had commercial applications already. However, until reliable, cost-effective, commercially applicable methods are more widely available, problems associated with mycotoxin contamination and the economic losses resulting, will continue to be seen in food and agriculture industries.

Coupling between external viscosity and the intramolecular dynamics of ribonuclease T1: a two-phase model for the quenching of protein fluorescence

Our recent equilibrium dialysis studies showed that proteins are able to interact preferentially with acrylamide (Punyiczki et al. (1993) Biophys. Chem. 47, 9-19). The presence of considerable amounts of acrylamide--albeit weakly bound--in the protein volume, coupled with the failure of a simple gating model of quenching to rationalise viscosity dependence of the quenching of tryptophan (Trp) fluorescence in Ribonuclease T1 (RNase T1) has prompted us to explore a new model, the two-phase model for quenching. According to this model, the dynamic quenching is accomplished by quencher molecules already in the protein phase at the moment of excitation. Some of the molecules may, at this moment, form an encounter complex with the fluorophore and thus be responsible for the observed static contribution. We use the rate equation derived from our model to study the viscosity dependence of acrylamide quenching of Trp fluorescence in RNase T1. The model allows us to separate co-solvent effects: the chemical effect on the protein and on the distribution of quencher molecules between the bulk and the protein phases and, further, the viscosity effect due to coupling between the bulk viscosity and the local friction affecting intramolecular fluctuations of the protein matrix. We express local friction in terms of bulk viscosity, eta, and a coupling constant kappa (friction = eta kappa). Addition of glycerol up to 65% is characterised by a kappa of 0.50. The viscosity dependence of the apparent bimolecular quenching constant is a combination of two compensating effects: changes in chemical activity and changes in patterns of structural fluctuations.

Ethanol attenuation of ganglioside sialylation and neuritogenesis

Neurite-producing cultured embryonic chick brain neurons in 96-h culture were exposed chronically to 25 mM ethanol for a 72-h period. Neurital plasma membrane extension was markedly attenuated in the ethanol-exposed neurons as compared with ethanol-free control cultures. The rate of biosynthetic sialylation of gangliosides, which are major structural sialoglycosphingolipid components in the exofacial lipid bilayer of the neurital plasma membrane, decreased to about half that in the alcohol-free neurons. The findings show that ganglioside sialylation in the morphodifferentiating central nervous system neuron is significantly attenuated by chronic exposure to a moderate dose of ethanol. Depression of ganglioside-dependent neuritogenesis may represent a mechanism for development of the central nervous system component of the fetal alcohol syndrome.

A prospective study on changes in the sensibility of the oral mucosa and the mucosa of the upper lip after Le Fort I osteotomy

A prospective study on 21 patients was performed in order to investigate the changes in the sensibility of the oral mucosa and the mucosa of the upper lip after a Le Fort I osteotomy. Patients were followed-up 1 month, 3 months and 6 months postoperatively. The sensibility of the mucosa was tested using electrical sensimetry (Laitinen, 1987). The teeth were tested with carbon dioxide snow (Obwegeser and Steinhäuser, 1963). A picture of the marked hypoaesthetic area was performed and magnified 1:1 if a hypoaesthesia of the cutaneous distribution of the infraorbital nerve was found. The area was measured using a Macintosh II CX computer. It was demonstrated, that after 3 months the infraorbital nerve regained its function completely. The greater palatine nerve and the posterior superior alveolar nerve demonstrated an incomplete recovery of sensory function after 6 months. After 6 months 92.8% of the teeth reacted to carbon dioxide snow. Within the first 6 months postoperatively, no pulpe necrosis was observed. No correlation could be found between the amount of anterior maxillary movement and the degree of hypoaesthesia of the infraorbital nerve. Dentate Le Fort I osteotomies showed a better sensory regeneration of the greater palatine nerve than edentulous Le Fort I osteotomies. After Le Fort I osteotomies in 2 parts, more hypoaesthesia of the greater palatine nerve was observed than after Le Fort I osteotomies in 1 part. After miniplate osteosynthesis, more hypoaesthesia of the posterior superior alveolar nerve was observed than after wire osteosynthesis. The results are discussed and compared with the results found in the literature.(ABSTRACT TRUNCATED AT 250 WORDS)

High indoor radon variations and the thermal behavior of eskers

Measurements of indoor radon concentrations in houses built on the Pispala esker in the city of Tampere were taken. The objective was to find connections between indoor radon concentrations, esker topography, and meteorological factors. The results show that not only the permeable soil but also subterranean air-flows in the esker strongly affect the indoor radon concentrations. The difference in temperature between the soil air inside the esker and the outdoor air compels the subterranean air to stream between the upper and lower esker areas. In winter, the radon concentrations are amplified in the upper esker areas where air flows out from the esker. In summer, concentrations are amplified in certain slope zones. In addition, wind direction affects the soil air and indoor radon concentrations when hitting the slopes at right angles. Winter-summer concentration ratios are typically in the range of 3-20 in areas with amplified winter concentration, and 0.1-0.5 in areas with amplified summer concentrations. A combination of winter and summer measurements provides the best basis for making mitigation decisions. On eskers special attention must be paid to building technology because of radon.

Changes in cardiovascular risk profile during the cessation of smoking

The present study evaluated the intraindividual changes of serum lipids, blood pressure, adrenergic stimulation, and platelet reactivity in chronic smokers undergoing controlled smoking cessation assisted by nicotine chewing gum. One hundred twenty-one healthy smokers, who had smoked at least 20 cigarettes a day for at least 5 years, were included in the study. Serum lipids, blood pressure, catecholamine concentrations in serum and urine, platelet volume and platelet function in vitro were assessed during an initial phase of continued smoking, after stopping smoking during nicotine gum chewing, and after abstaining from both smoking and gum chewing. After a median of 11 weeks of chewing nicotine gum, 52 persons (43%) remained abstinent from smoking and chewing for at least 12 weeks. In these successful study participants, low-density lipoprotein (LDL)-cholesterol levels decreased significantly by a mean of 7.5 mg/dL (5.6%). High-density lipoprotein (HDL)-cholesterol increased by 5 to 6 mg/dL during the first weeks after ceasing to smoke, but levels at the end of study were only 2.1 mg/dL (3.4%) higher than baseline (nonsignificant difference). Triglyceride levels did not change during smoking cessation. While systolic blood pressure remained unchanged, diastolic blood pressure increased significantly by a mean of 3.5 mm Hg. For LDL-cholesterol, HDL-cholesterol, and systolic and diastolic blood pressure, there was an inverse correlation between the respective baseline values and the observed changes during the cessation of smoking. The urinary excretion of adrenaline and noradrenaline decreased upon quitting. The volume of platelets became significantly less during smoking cessation, but aggregation induced by adenosine diphosphate (ADP) and collagen and thromboxane synthesis in vitro remained uninfluenced. The platelet cyclic adenosine monophosphate (cAMP) response to stimulation of adenylate cyclase with prostaglandin E1 showed marked enhancement upon quitting. The changes observed intraindividually during smoking cessation largely correspond to the differences between smokers and nonsmokers described in epidemiologic studies. For serum lipids and blood pressure, a significant dependence of the changes on the respective values at baseline may indicate greater benefit for persons at higher risk. Decreased platelet volume and increased susceptibility of platelets to antiaggregatory prostaglandin E1 indicate a favorable influence of quitting on platelet reactivity.

Connective tissue tumors in patients with cutaneous melanoma

BACKGROUND

A possible relation between cutaneous melanoma and connective tissue tumors has been described.

OBJECTIVE

After the observation that a group of our patients had both cutaneous melanoma and a soft tissue sarcoma, we elected to review this formally. Eleven patients with both diagnoses were identified and are described.

METHODS

A computer search through the Medical Records Department and the Tumor Registry of the Massachusetts General Hospital identified seven men and four women with the diagnoses of melanoma and malignant bone or soft tissue sarcoma. The medical records and pathology specimens of all tumors were reviewed.

RESULTS

In three patients, the two tumors were diagnosed within 1 year of each other, in seven, the diagnosis of melanoma was made first, and in one, melanoma was diagnosed after the connective tissue lesion. The interval between the two diagnoses ranged up to 13 years. Although the locations and types of melanoma were typical, some of the connective tissue tumors were unusual; there were two sacral chordomas. In two instances, the melanoma and connective tissue tumor were anatomically close; the sarcoma developed at the edge of the resection of the prior melanoma in one patient. None of the tumors developed in previously irradiated tissues, and in no instance did the second tumor appear to be caused by the therapy received for the first. None of the patients had a family history of melanoma. Four patients had other cancers in addition to the melanoma and connective tissue tumor.

CONCLUSION

Although these patients were seen in a referral center, it is our impression (based on the total number of patients with connective tissue tumors seen and the incidence of melanoma in the general population) that observing 11 patients with both types of tumors is greater than would be expected by chance.

Regression of experimental Burkitt's lymphoma induced by Epstein-Barr virus-immortalized human B cells

Epstein-Barr virus (EBV)-immortalized human B cells survive only transiently when injected subcutaneously into athymic mice, whereas Burkitt's lymphoma cells give rise to progressively growing subcutaneous tumors. In this study, we tested whether these Burkitt's tumors could be induced to regress via a bystander effect induced by EBV-immortalized B cells. Simultaneous inoculation of EBV-immortalized B cells and Burkitt's lymphoma cells in the same subcutaneous site resulted in tumors that regressed with necrosis and scarring. Similarly, simultaneous inoculation of EBV-immortalized B cells and Burkitt's lymphoma cells in separate subcutaneous sites resulted in regression of a proportion of the Burkitt's tumors. Furthermore, most of the established human Burkitt's tumors regressed with necrosis and scarring after intratumor inoculations with EBV-immortalized B cells. The EBV-immortalized B cells continued to exert this antitumor effect even when killed with irradiation. The experimental approach to Burkitt's lymphoma treatment described here exploits the ability of athymic mice to reject EBV-immortalized B cells to target an effective antitumor response to malignant cells normally incapable of eliciting it.

Gorham's massive osteolysis: the role of radiation therapy and a review of the literature

PURPOSE

This paper reviews the natural history and management of patients with Gorham's disease and presents four cases treated at The Massachusetts General Hospital since 1965. Gorham's disease is characterized by localized endothelial proliferation which results in destruction and resorption of bone. The etiology is undefined. There is no evidence of a malignant, neuropathic, or infectious component. This disease is progressive in most patients, but in occasional instances the process has been noted to be self-limited. The principal treatment modalities are surgery and radiation therapy.

METHODS AND MATERIAL

Since 1965, four patients with Gorham's Disease have been treated at the Massachusetts General Hospital. Three received definitive radiation therapy in doses ranging from 31.5 to 45 Gy. The fourth patient underwent surgery primarily.

RESULTS

Three patients are currently alive and fully functional with no evidence of disease at last follow-up. The fourth patient died of progressive disease despite treatment with both radiation therapy and surgery.

CONCLUSION

The prognosis for patients with Gorham's disease is generally good unless vital structures are involved. Due to the rarity of this entity, there is no standard therapy. Definitive radiation therapy in moderate doses (40-45 Gy in 2 Gy fractions) appears to result in a good outcome and few long-term complications.

Breast cancer: options for older patients

Despite being at high risk of breast cancer, elderly women tend not to be screened systematically or treated aggressively. Elderly patients should be instructed in breast self-examination and encouraged to have annual mammograms. Biopsy options have increased and include newer techniques of needle localization, ultrasound localization, and stereotactic biopsy. Treatment options are wide-ranging, including increased emphasis on breast preservation in patients with stage I and stage II disease.

Should titanium miniplates be removed after bone healing is complete?

A prospective study of 32 patients was performed to analyze black pigmentation in the soft tissue covering titanium miniplates. This soft tissue was compared with the soft tissue covering Champy stainless steel plates. All plates were removed 8 months after application. Macroscopically visible pigmentation was found in 25.6% of the soft tissue covering titanium miniplates and in none of the soft tissue covering Champy stainless steel plates. Microscopically visible pigmentation was found in 71.8% of the soft tissue covering titanium miniplates and in 65.3% of the soft tissue covering Champy stainless steel plates. Energy-dispersive x-ray analysis of the soft tissue covering titanium miniplates revealed only the presence of titanium dioxide. In the soft tissue near Champy stainless steel plates, chromium, nickel, iron, and molybdenum were found. Electron microscopy showed titanium dioxide to be mainly deposited between the collagen fibers, whereas stainless steel particles were mainly found in giant cells.

Revision of the acetabular component without cement after total hip arthroplasty. Three to six-year follow-up

One hundred and thirty-eight consecutive revisions of an acetabular component were performed in 132 patients between 1983 and 1986. The revision prosthesis was a hemispherical component that was coated with porous titanium mesh and was secured to the pelvis with a variable number of screws. There were seventy-five women and fifty-seven men, and the mean age at the time of the revision was fifty-two years (range, twenty to seventy-nine years). Due to defects in the acetabulum, 80 per cent of the hips were treated with bone grafts, usually a mixture of local autogenous graft and freeze-dried allograft. One hundred and twenty-four patients (129 hips) were available for follow-up, at a mean of forty-four months (range, thirty-six to eighty months). Seven hips (5 per cent) were revised again: four because of infection and three because of instability. There were no revisions for loosening without infection, and none of the components migrated in the absence of infection. Radiolucent lines were common and usually corresponded to regions in which allograft had been used. All bone grafts united by twelve months. Non-contained medial grafts underwent a phenomenon of resorption, consolidation, and remodeling to a sclerotic rim by twenty-four months. There were no complications related to placement of the screws. The results in this series were superior to results of revisions of acetabular components with the use of cement, which were associated with rates of failure of almost 10 per cent after a similar duration of follow-up. The technique of maximization of host-bone coverage and of packing of all defects with cancellous autogenous graft or allograft, or both, was successful for all classes of acetabular deficiencies.

Preoperative radiation, surgical margins, and local control of extremity sarcomas of soft tissues

The relationship between status of the surgical margin and local control of soft tissue sarcoma of the extremities by preoperative radiation therapy has been assessed in 132 consecutive patients from 1974 to 1988. The 5-year actuarial local control rate was 94% for all patients; the rates were 97% and 82% for the 104 tumors with negative margins and the 28 tumors with positive margins, respectively. The local control rate was independent of the extent of the negative margin. For primary sarcomas, the local control rates were 96%, 97%, and 100%, respectively, for margins that were negative at < or = 1 mm or > 1 mm, or the specimens were negative for tumor; for positive margins the result was 83%. The overall local control rate was lower (not significant) for recurrent than for primary sarcomas: 88% vs. 94%. On the other hand, when stratifying by margin status, no difference was observed in local control results, i.e.: (1) 97% and 91% for primary and recurrent tumors with negative margins, respectively, and (2) 83% and 80% for primary and recurrent tumors with positive margins, respectively. Local control was not significantly higher in those patients who were treated by surgical resection (S), radiation (RT), and re-excision of the previous tumor bed than in those whose radiation therapy was started after the biopsy and followed by one surgical resection. For primary sarcomas that were resected with negative margins the results were: 100% of 15 patients treated by S-RT-S and 96% of 75 patients treated by RT-S.

Felbamate: a double-blind controlled trial in patients undergoing presurgical evaluation of partial seizures

We studied the efficacy and safety of felbamate, an investigational antiepileptic drug, in a unique, double-blind, placebo-controlled trial. Sixty-four patients with refractory partial-onset seizures who completed a routine evaluation for epilepsy surgery met seizure frequency entry criteria. Each patient received felbamate or placebo in addition to the anticonvulsant regimen present at the conclusion of the presurgical evaluation. The treatment phase consisted of an 8-day inpatient period and a 21-day outpatient period. The efficacy variable was time to fourth seizure. The difference in time to fourth seizure was statistically significant (p = 0.028) in favor of felbamate. Eighty-eight percent of the patients in the placebo group had a fourth seizure during the treatment phase compared with 46% of the patients in the felbamate group (p = 0.001). Adverse experiences with felbamate were generally mild or moderate in severity. This trial demonstrated the ability of felbamate to quickly and safely reduce the occurrence of frequent partial-onset seizures and maintain effective seizure control following reductions in the dosages of standard antiepileptic drugs.

Inhibition of neuritogenic ganglioside biosynthesis in chick brain neurons by calcium ionophore A23187

Treatment with Ca++ ionophore A23187 blocks biosynthesis of the major terminally (IV3) sialylated higher species of neuronal gangliosides: GD1A, GT1B, GQ1B, and Gp, key components in the plasma membrane of neurite-bearing neurons. At the same time, the neurital field diminishes markedly, resulting in neuronal reversion to pre-neuritogenic morphology. A23187 causes no biosynthetic loss of any of the simpler gangliosides that constitute the plasma membrane of pre-neuritogenic neurons, nor of ganglioside precursors leading to formation of the blocked gangliosides. The data indicate that A23187 significantly reduces neuritogenic ganglioside biosynthesis.

Felbamate monotherapy: controlled trial in patients with partial onset seizures

Felbamate (FBM) monotherapy was evaluated in 44 patients with uncontrolled partial onset seizures in a unique, single-center, randomized, double-blind, parallel-group trial. During the 56-day baseline period, patients were required to have at least 8 seizures and to be receiving only one standard antiepileptic drug (AED) at a therapeutic level; a second AED was allowed if at a subtherapeutic level. Patients were randomized to valproate (VPA), 15 mg/kg, or to FBM, 3,600 mg/day. In the treatment phase, previous AEDs were discontinued by study day 28 (by one-third decrements on study days 1, 14, and 28). Study end points were completion of 112 study days or the fulfilling of escape criteria. Criteria for escape relative to baseline were: two-fold increase in monthly seizure frequency, two-fold increase in highest 2-day seizure frequency, single generalized tonic-clonic seizure (GTC) if none occurred during baseline, or significant prolongation of GTCs. The predetermined primary efficacy variable was the number of patients escaping in each treatment group. Nineteen patients on VPA and 3 on FBM met escape criteria (p less than 0.001, chi-square test). When overall seizure frequency among study completers was compared with baseline, the FBM group had a 50 to 65% reduction in seizure frequency. FBM adverse experiences were all mild or moderate in severity, and the incidence of adverse experiences was lower in monotherapy. FBM monotherapy was effective in the treatment of partial onset seizures with or without generalization and demonstrated a favorable safety profile.

Regulation of phosphoinositide hydrolysis in cultured astrocytes by sphingosine and psychosine

The effects of sphingosine and psychosine on phosphoinositide hydrolysis in primary cultured astrocytes were determined. Exposure to sphingosine produced a dose-dependent stimulation of phosphoinositide hydrolysis requiring the presence of external Ca++ for optimal activity. The addition of 10 microM norepinephrine resulted in a stimulation additional to that with sphingosine. The alpha 1-antagonist prazosin completely inhibited norepinephrine-induced phosphoinositide hydrolysis but had no effect on that produced by sphingosine. Psychosine (108 microM), when co-incubated with sphingosine, produced complete inhibition of sphingosine-induced phosphoinositide hydrolysis at all doses of sphingosine tested (33-668 microM). Likewise, psychosine totally inhibited norepinephrine-induced phosphoinositide hydrolysis. The protein kinase C inhibitor staurosporine (1 microM) had no effect on sphingosine-induced phosphoinositide hydrolysis. These findings suggest that lysosphingolipids such as sphingosine and psychosine may play an important role in the regulation of phosphoinositide turnover in astrocytes by a mechanism dependent on extracellular Ca++ and independent of the alpha 1-adrenergic receptor and protein kinase C.

Developmental patterns of ganglioside sialosylation coincident with neuritogenesis in cultured embryonic chick brain neurons

Chick brain precursor neurons were observed to introduce sialic acid biosynthetically into only three specific gangliosides: monosialosyl lactosyl ceramide (GM3), disialosyl lactosyl ceramide (GD3), and disialosyl gangliotrihexosyl ceramide (GD2), when sialic acid was labeled metabolically by its obligate precursor, [3H] ManNAc. Sialosyl donor CMP-[3H]NeuAc supplied in the culture medium gave rise uniquely to surface-labeled GD3. Thus sialosyl transferase/GD3 synthase activity is expressed both intraneuronally and in the neuronal exofacial surface. Upon epidermal growth factor-induced onset of neurite outgrowth, labeled complex sialosyl gangliotetrahexosyl ceramide species of gangliosides began to appear in the embryonic neuronal plasma membrane. However, intraneuronal and exofacial sialosyl transferase/GD3 synthase activities remained constant, with or without neurite outgrowth. Moreover, simpler species of gangliosides maintained a steady quantitative sialosyl level (1.6 +/- 0.2 micrograms of sialic acid/mg of protein), whereas more complex species completely absent before neurite outgrowth accrued and reached 4.8 +/- 0.9 micrograms of sialic acid/mg of protein with full neurite development. This analysis of developmental patterns of ganglioside sialosylation has provided evidence that stable neurite outgrowth depends upon generation by the neuron of special plasma membrane with a massive content of complex higher species of gangliosides.

Somatic gene transfer in the development of an animal model for primary hyperparathyroidism

The overproduction of hormones is associated with a variety of endocrinological disorders. We have used somatic cell gene transfer of human PTH (hPTH) to develop an animal model of hypercalcemia and osteoclastic skeletal resorption. Recombinant retroviruses were used to transduce a functional hPTH gene into cultured rat fibroblasts. The recombinant-derived preproparathyroid hormone peptide was appropriately processed in this ectopic cell, and intact hPTH (1-84) was secreted at a high level (2-5 ng/10(6) cells/24 h). Transplantation of the PTH-secreting cells into syngeneic rat recipients was associated with the development of hypercalcemia mediated by increasing serum concentrations of hPTH. Thyroparathyroidectomy in these hypercalcemic rats producing hPTH did not result in hypocalcemia and tetany, which was observed in control animals undergoing thyroparathyroidectomy. Chronic overproduction of hPTH (60 days) was associated with severe hypercalcemia, metastatic calcification, and histological changes of osteoclastic resorption of bone. This animal model will be useful in studying the pathophysiology of severe hyperparathyroidism in humans and should help in the evaluation of new medical therapies for hypercalcemia.

Viscosity dependence of acrylamide quenching of ribonuclease T1 fluorescence. The gating mechanism

The structural regulation of the access of acrylamide molecules, as quenchers, to the buried tryptophans of a protein can be modelled by a simple gate concept. Such a gate, when open, allows transient exposure of the fluorophore to the quencher molecule in solution. We have previously shown that the observed viscosity dependence of acrylamide quenching process in ribonuclease T1 (RNAse T1) is not reconcilable with the gating mechanism. However, on that occasion, we neglected the effect of changes in the activity of the quencher molecule and the possible presence of static quenching. The experimental observation of a considerable contribution by static quenching and the realization that static quenching might produce dramatic effects in steady state measurements led us to reexamine the question. It is shown that in a gating model the static component can also influence the apparent dynamic quenching. In this paper, we present derived equations for the gated quenching mechanism including possible contributions from the static component. We also carefully remeasured the acrylamide quenching of RNAase T1 as a function of increasing glycerol concentration. Computer simulations were carried out to compare the experimental data set to the generalized model. We reach the conclusion that even the new, quite complex equations fail to predict the qualitative and quantitative features of the observed quenching experiments. We arrived at the conclusion that the fluorophore is never the target of the quencher molecules in solution.

The effect of viscosity on the accessibility of the single tryptophan in human serum albumin

When reactions take place with one of the reactants tied to protein matrix, movements along the reaction coordinate towards the transition state can become coupled to structural fluctuations of the protein matrix. This investigation aims to test the assumptions underlying the arguments supporting such a coupling. A coupling is allowed only if the activation barrier is high and broad enough as shown to be the case for the proton catalyzed isotope exchange at Trp-63 of lysozyme. In the present investigation the activation barrier for the same reaction has been lowered radically in an effort to show that the coupling, as measured by the dependence of rate on solution viscosity, will diminish and ideally vanish, despite the unchanged effects of cosolvents on the chemical activities of all the reactants. The isotope exchange rate at the indole nitrogen of the single tryptophan residue of human serum albumin was measured with UV. This residue is rigidly held to the protein surface and the solvent access, although restricted, corresponds to a partially exposed residue. As a consequence, the isotope exchange rates and the bimolecular quenching rate of fluorescence by acrylamide, also measured, are high. The experiments were carried out at pH 5.2 where the molecule is in the N-form and the exchange is catalyzed by OH- ions. The activation energy of the hydroxyl catalyzed reaction is 22 kJ lower than for the proton catalyzed process. Under these conditions the exchange rate is viscosity independent both in the case of glycerol and in ethylene glycol.(ABSTRACT TRUNCATED AT 250 WORDS)

The coupling of catalytically relevant conformational fluctuations in subtilisin BPN' to solution viscosity revealed by hydrogen isotope exchange and inhibitor binding

We have measured the tritium outexchange of subtilisin BPN'. A consistent and rather small group of hydrogens was isolated by their sensitivity to inhibitor binding. The viscosity dependence of exchange from these inhibitor protected hydrogens was then examined in 0.05 M MES buffer, pH 6.5 and 10 degrees C. The viscosity of the reaction medium was varied by added glycerol and ethylene glycol. The exchange rates were corrected to be compared at identical hydroxyl ion and water activity. The salient observation is the strikingly similar viscosity coupling behavior when compared to the deacylation step of ester hydrolysis catalyzed by the same enzyme (Ng and Rosenberg, Biophysical Chemistry, 39 (1991) 57). We have obtained a viscosity coupling constant of 0.68 -/+ 0.18 for hydrogen exchange in glycerol (cf. 0.65 -/+ 0.11 for deacylation in glycerol, sucrose, glucose and fructose); 1.67 -/+ 0.07 for outexchange (cf. 1.92 -/+ 0.09 for deacylation), in the presence of ethylene glycol. The two reactions are very chemically dissimilar, yet they show very similar viscosity coupling behavior. This together with the well established role of structural fluctuations in hydrogen exchange implies a similar role of structural fluctuations in the deacylation step of subtilisin BPN' catalyzed ester hydrolysis.