DNA motions in the nucleosome core particle

We have used time-resolved triplet state anisotropy decay techniques to measure the conformational flexibility of DNA in the nucleosome. From these measurements we conclude that, in a nucleosome, the DNA helix experiences substantial internal flexibility, which occurs with a time constant near 30 nsec. We find that our data can be fit well by a modified version of the Barkley-Zimm model for DNA motion, allowing only DNA twisting motions and the overall tumbling of the nucleosome. That fit yields a calculated torsional rigidity equal to 1.8 X 10(-19) erg X cm, a value equal to that measured for uncomplexed DNA. We conclude from such similarity that large, fast twisting motions of the DNA helix persist, nearly unaltered, when DNA is wrapped to form a nucleosome.

Isolation and properties of L-amino acid oxidase from Ophiophagus hannah venom

This paper reports the isolation and some properties of L-amino acid oxidase from Ophiophagus hannah venom. The differences between L-amino acid oxidase from Ophiophagus hannah and that from other sources in specific activity, properties and the spectrum of isozymes are noticeable. The result of electrophoresis on polyacrylamide gel shows that this purified enzyme is homogenous. The molecular weight determined by gradient polyacrylamide gel slab (4--30%) is around 15 X 10(4) dalton. The molecular weight of the subunit determined by SDS gradient gel electrophoresis (4--30%) is around 7.3 X 10(4) dalton. Therefore, this enzyme is composed of two subunits. The absorption spectrum reveals that there are two FADs in each molecule. The optimum pH of enzymic reaction is around 8.7--9.0 when L-leucine is used as substrate. The inhibition of the products is noticeable when substrate concentration goes beyond 3mM. This enzyme is heat stable and its activity would not decrease obviously after heating at 55 degrees C for 40 min. A linear relationship between enzyme concentration and reaction rate was noticed when enzyme concentration was below 5.7 micrograms/ml.

Molecular motion of DNA as measured by triplet anisotropy decay

We have used triplet anisotropy decay techniques to measure the internal flexibility and overall rotational motion of DNA, covering a time range from 15 ns to 200 mus. Nearly monodisperse DNA fragments 65--600 base pairs long were studied by using the intercalating dye methylene blue as a triplet probe. We found that the slow end-over-end tumbling of short DNA fragments (less than or equal to 165 base pairs) is as predicted for a rigid rod. As expected, a longer DNA fragment (600 base pairs) experiences slow segmental motion of its helix axis. We found that, at the earliest times, anisotropy decays more rapidly than expected for a rigid rod, suggesting that, when bound, methylene blue monitors fast internal motion of the helix. Since the rod-like end-over-end tumbling of short fragments rules out fast bending motions, we conclude that the fast components of DNA anisotropy decay are due to twisting motion of the helix, occurring with a time constant near 50 ns.

Body composition in affective disorder before, during, and after lithium carbonate therapy

The body composition of three unipolar and 17 bipolar patients, studied during the depressive state, was compared with that of 48 controls. The ratio of extracellular to intracellular water content was significantly less in male patients than in male controls: the difference between female patients and female controls was not statistically significant. In patients of both sexes, residual sodium concentration was greater in patients than in controls. The intracellular content of potassium was the same in patients as in controls. In six patients, body composition was studied prior to lithium carbonate therapy, after 17 days of treatment, and 17 days after discontinuing administration of the drug. The significant changes were a decrease in body weight during therapy, and a decrease in body water content and an increase in residual sodium concentration after drug treatment was discontinued.

Body composition measurements in normal man: the potassium, sodium, sulfate and tritium spaces in 58 adults

The aqueous phase of total body composition varies with sex, and changes with age, necessitating age, sex and method-specific normal values. Consensus has developed for the methods most suited to clinical studies. 3H20 for water, 35SO4 for ECW, 24Na for NAc, and 40K for body potassium were used in 58 normal volunteers aged 19-80, 30 men and 28 women. This report shows significant age regressions in both sexes for total body water and intracellular water, and for both Na and K when referenced to body water. Combination of these findings with the highly age related decrease in total body potassium confirms previous studies that body cell mass decreases with age. Intracellular K+ and Na+ at the zero age intercept are 130 and 14.5 for males, and 124 and 24mEq/1 for females respectively. Secular decrease in K+ and increase in Na+ concentrations in the average cell are suggested although not established. Values for normal body composition, in subjects healthy by all available criteria are in some instances age and sex dependent, but in all parameters except fat show wide normal range (SD = 7% of mean) which derive more from biological variation than from limitations of measurement precision. However, use of body water rather than weight succeeds in narrowing this wide range, and is a more logical denominator which is readily subject to accurate measurement. In serial studies of the same subject, significant changes can be measured which are well within the normal range.

A possible low intracellular potassium in obesity

In comparison with lean marathon runners whose fat content was 15%, obese subjects with a fat content of 55% showed a 36% reduction in intracellular potassium. It is hypothesized that as much as 60% of this decrease may have been due to the lower proportion of muscle (which has the highest intracellular potassium of any tissue) in the fat free mass of very obese subjects. The remainder of the decrease seems to have been a measurement artefact owing to self-absorption of gamma rays by adipose tissue, most of which is distributed over potassium rich lean tissue. The low intracellular potassium values found in obesity should not be interpreted as necessarily signifying potassium deficiency.

Combined effects of alcohol and lithium on body composition in the rat model

Alcohol markedly enhances Li+ retention in blood and muscle in rats taking Li and alcohol. The marked enlargement of the exchangeable Na+ space which occurs with alcohol alone, Li+ alone, and to an even greater extent with combined therapy, results from extensive mobilization of "bound" bone sodium, which is transferred to intracellular sites, demonstrably in skeletal muscle, and presumably in other cells. This 87% increase in measured intracellular Na+, and concomitant decrease in K+, would be predicted to produce profound effects on the intracellular ionic milieu, and on membrane function. Lithium is associated with a decrease in food and fluid intake, and this effect is enhanced by alcohol. However the decrease in intake did not result in nutritionally significant deficits in either group, and therefore the observed abnormalities in body composition did not result from caloric, protein, K, Na, or Ca deficiency.

Metabolism of calf trabecular (reticular) meshwork

It has been found that calf eyes are an excellent source of trabecular meshwork tissue for biochemical studies. Homogenates of pooled meshwork were centrifuged at 27K X g and 1.5K X g. The high-speed supernatants produced lactate at 0.35 mumole/min/gm tissue in the presence of hexokinase-saturating concentrations of glucose (10 mM) at pH 7. The optimum pH was 7.6. In the absence of ammonia, lactate could be produced from fructose 1,6-diphosphate but not from glucose or glucose 6-phosphate. The optimum ammonia concentration was 1 to 2 mM. Lactate was produced at an even greater rate from fructose, but only poorly from sorbitol or galactose (all at 10 mM). The activity of hexokinase, glucose 6-phosphate dehydrogenase and UDPG dehydrogenase was measured. Fructokinase could not be detected. The low-speed supernatant readily oxidized succinate, malate, and glutamate at about 0.012 muAtO/min/gm tissue. The oxidative rate in vivo is estimated to be about one third of this. These results demonstrate that knowledge of the normal metabolism of calf trabecular meshwork may be obtained with relative ease, with possible important implications for understanding the disease of glaucoma.

Effect on body water of running 10 miles

Despite a 2.3% weight loss in 10 men who ran 10 miles, extracellular water (ECW) increased by 3.5%. Total body water (TBW) measured as tritium space increased by 2.4%, and intracellular water (ICW), inferred as the difference between TBW and ECW, increased by 1.8%. The increase in tritium space probably represents increased nonaqueous hydrogen exchange in the postexercise period ond casts doubt on the validity of TBW and ICW when measured immediately after exercise.

Humoral and cellular immune responses in Aspergillus fumigatus pulmonary disease

This study was designed to evaluate immunologic differences between aspergilloma (A) and allergic bronchopulmonary aspergillosis (ABPA), comparing the results to atopic and nonatopic control subjects. Humoral studies included skin tests with common inhalant antigens and Aspergillus fumigatus. Total and specific IgE and other immunologlobulin levels and serum precipitins were evaluated against A. fumigatus. Cellular immunity was studied with routine skin testing and phytohemaqglutinin-induced lymphocyte blast transformation. Antigen-induced blast transformation was also carried out with the use of serial dilutions of A. fumigatus. All patients with ABPA were atopic and had marked elevations of IgE. None of the patients were atopic and they had normal IgE levels. Immediate and late skin reactivity to A. fumigatus was low in control and A groups but high in 2 patients with ABPA. IgG antibody against A. fumigatus was generally greater in the ABPA group. Both ABPA and A had serum precipitating antibody against A. fumigatus. The atopic controls had elevated IgE levels and immediate skin test reactivity to A. fumigatus, and one also had weak serum precipitins against A. fumigatus. IgE antibody against A. fumigatus was generally higher in ABPA than A. ABPA and A patients had elevated stimulation indices (SI) to A. fumigatus. No stimulation could be detected with cells from control subjects. This study indicates that both T and B cell sensitization may play a role in the development of or as a response to aspergillus-related pulmonary disease.

Extracellular water measurements: organ tracer kinetics of bromide and sucrose in rats and man

Bromide and sucrose distributions were measured as functions of time after tracer injection into 14 rat organs that accounted for 93% of body wt, with the goal of evaluating the use of bromide and sucrose as tracers for the extracellular water volume (ECW). The tracers, Na, 82Br, 125I-labeled human serum albumin, [14C]sucrose, and 3H2O, were used to calculate bromide and sucrose content in red cells, plasma, and 13 blood-free organs. Selective concentration of Br- occurs in RBC, stomach, and skin, accounting in part for the discrepancy between the Br- space and the smaller ECW volume as derived from other methods. Sucrose is rapidly metabolized in the rat and its 14C tracer cannot be used for ECW determination in this species. The kinetics of Br- distribution were estimated in rats and in 16 human subjects by measuring plasma disappearance values and specific organ uptakes. A pharmacokinetic compartmental model was derived, containing explicit parameters for blood flow, diffusion constants, and ECW spaces separately for each organ. Precise fitting of experimental bromide data was achieved for the rat; satisfactory fitting was also achieved in man from more limited plasma and biopsy data.

The quantification of IgE antibody specific for ragweed Antigen E (AgE) on the basophil surface in patients with ragweed pollenosis

IgE antibody specific for AgE (IgE—AgE) was eluted from human basophils at acid pH and quantified by its binding of ¹²⁵I AgE in antigen excess. The quantity of Ige—AgE recovered from 30 ml of blood ranged from 0.08 ng to 10.3 ng representing 500 to 56,000 molecules IgE—AgE per basophil. The number of molecules of IgE—AgE per basophil was compared to plasma IgE—AgE, total plasma IgE and leucocyte histamine release in response to AgE.

The ratio of plasma IgE—AgE to basophil bound IgE—AgE ranged from 100 to 4000, indicating that there are a limited number of IgE receptors on the basophil surface as contrasted to the concentration of IgE in the plasma. There was no correlation between IgE—AgE in plasma and the number of molecules of IgE—AgE per basophil. However there was a significant correlation between the ration of IgE—AgE to total IgE in plasma and the number of IgE—AgE molecules per basophil.

Two measures of leucocyte histamine release in response to AgE, cell reactivity (maximum per cent histamine release attainable) and sensitivity (lowest antigen dose leading to 50% release), were compared to the number of IgE—AgE molecules per basophil. Cell reactivity was dependent on the number of IgE—AgE molecules per basophil. Only 2500 molecules IgE—AgE per basophil were required to reach a cellular reactivity of 50%. Cell sensitivity to AgE was not correlated with the number of molecules IgE—AgE per basophil which indicated that other factors played a role in determining the sensitivity of a population of basophils to antigenic stimulation by AgE.

Serum calcium, magnesium, phosphorus, alkaline phosphatase and 25-hydroxyvitamin D concentrations in children

Serum calcium, magnesium, phosphorus, alkaline phosphatase and 25-hydroxyvitamin D concentrations for Coloured children between the ages of 1 and 17 years are reported. No evidence of vitamin D deficiency was found. The problem of the interpretation of 'normal' alkaline phosphatase concentrations is highlighted.

The assessment of immunologic and clinical changes occurring during corticosteroid therapy for allergic bronchopulmonary aspergillosis

Twenty-two patients with allergic bronchopulmonary aspergillosis have been treated and evaluated for a period ranging from two months to nine years. Twelve are available for periodic blood sampling. Data are presented suggesting the following: (1) Patients with allergic bronchopulmonary aspergillosis have high initial levels of total serum immunoglobulin E (IgE). These levels are significantly higher in those patients who had not been previously treated with prednisone for the control of asthma. (2) Treatment with alternate day prednisone (0.5 mg/kg given on alternate days) caused clinical and roentgenologic improvement as well as marked decreases in total serum IgE but does not necessarily prevent recurrence of the disease. (3) Total and specific IgE against Aspergillus antigen may increase prior to and during exacerbations of disease. (4) Specific IgG and IgE against Aspergillus antigen are increased in most patients with allergic bronchopulmonary aspergillosis and reflect disease activity as evidenced by x-ray and clinical exacerbations in some cases. (5) Lymphocyte transformation using Aspergillis antigen, as measured by the whole blood technic, is present in patients with allergic bronchopulmonary aspergillosis, but serial changes in lymphocyte transformation do not correlate with disease activity. (6) Precipitin reactions are present in patients with allergic bronchopulmonary aspergillosis, but presence or absence does not reflect disease activity in most cases.

Rickets in children of rural origin in South Africa: is low dietary calcium a factor?

Studies of nine children 4 7/12 to 13 years of age who had rickets are presented. No evidence of renal abnormalities, vitamin D deficiency, or of the inherited varieties of rickets was found. The salient features were their rural origins, mild hypocalcemia with evidence of secondary hyperparathyroidism, and improvement with a normal diet that contained an average of 944 mg calcium/24 hours. It is proposed that the etiology of the rickets is related to low calcium intake with or without a high oxalate concentration in the diet.

Radiation sensitivity of cultured human glioblastoma cells

Glial cells from 2 normal brains and 9 astrocytomas were cultured in vitro. The most rapidly proliferating cell lines were obtained from Grades III-IV astrocytomas. Normal glia proliferated slowly and growth ceased after 20 to 40 generations. The response of 3 Grade III-IV lines to graded doses of radiation was determined by colony formation and end point dilution technique. Two of the 3 lines were relatively radioresistant compared to other human cell lines; this may partially account for the radiation resistance of high grade astrocytoma tumors.

Estimation of composition of weight loss in man: a comparison of methods

Five different procedures were used to estimate composition of weight loss by six obese individuals maintained on low-calorie regimens: 1) energy-nitrogen (E-N) balance; 2) total body water-nitrogen balance (TBW-N); 3) total body water (TBW); 4) total body potassium (TBK); and 5) an anthropometric method. Quantity of weight lost by obese subjects during comparison periods lasting 25-40 days ranged from 7.9 to 17.1 kg. Expressed as percent of aggregate weight loss, collective fat loss was 47.6 by E-N balance; 46.3 by TBW-N balance; 51.7 by TBK; 50.9 by anthrometry; and 33 by TBW. The E-N balance method yielded a tight cluster of individual means, whereas the other procedures gave a wide scatter of means. For short-term studies, the E-N balance procedure, although tedious and difficult, should yield results less variable than those generated by any of the other methods examined.

Serum levels of 25-hydroxycholecalciferol as a diagnostic aid in vitamin D deficiency states

The measurement of serum levels of 25-hydroxycholecalciferol in the diagnosis of rickets is discussed in the light of recently acquired knowledge of vitamin D metabolism. A useful clinicopathological classification of rickets is presented and various aetiological mechanisms are discussed.

A competitive protein-binding assay for 25-hydroxyvitamin D

1. We describe a modified competive protein-binding assay for 25-hydroxyvitamin D, which does not require the prior separation of vitamin D from 25-hydroxyvitamin D. 2. Bovine albumin was used in the buffer, at a concentration of 1mg/ml, as a protein stabilizer and lipid solubilizer. Bovine albumin from different manufactures produced very different non-specific binding of 25-(3H)hydroxycholecalciferol (ranging from 3.3 per cent to 58.9 per cent). 3. The mean concentration of 25-hydroxyvitamin D in sera from normal children in Johannesburg was 76.75 +/- 24.75 mumol/ml (30.7 +/- 9.9 ng/ml).

Disparate hydration of adipose and lean tissue require a new model for body water distribution in man

The intra and extracellular fluid spaces in adipose tissue were determined by by 3H2O, 82Br-(minus), and 35SO4= uptake, and by appropriate chemical methods, in surgical biopsy material from 16 patients undergoing elective laparatomy. Total water space for adipose tissue was 14 +/- 1.4%: extracellular component was 11 +/- 1.1% in mesenteric and subcutaneous depots. Use of these adipose tissue hydration constants, combined with measurements of total body water (TBW), extracellular water (ECW), total body potassium, and experimentally derived age-specific constants for lean body potassium content, permits development of a four compartment model for body water which considers intra and extracellular components separately for adipose (AT) and adipose-free (AFM) tissue masses. This model has the form (see journal) where x is the total hydration and y the extracellular hydration of the adipose-free mass. The equations can be solved for the ECW and ICW of the adipose-free mass, defined by its potassium content. In four normal subjects, x was measured as 0.80 +/- 0.032, and y as 0.24 +/- 0.017. Thus, the adipose free mass, compared with adipose tissue, has approximately six times the total water and twice the extracellular water content per unit weight.

Reaction of 1,3-bis(2-chloroethyl)-1-nitrosourea with synthetic polynucleotides

The antitumor agent BCNU (1,3-bis(2-chloroethyl)-1-nitrosourea) was incubated with poly(C) and poly(G) in aqueous solution at 37 degrees and pH 7 to produce approximately 0.33 and 0.07% substitution, respectively. Under the same conditions, there was relatively little reaction with poly(A) and poly(U). Poylnucleotides reacted with [14C]BCNU were digested by chemical and enzymatic methods, and the derivative nucleotides were isolated by column chromatography. There were identified by a combination of ultraviolet and mass spectroscopy as 3-(beta-hydroxyethyl)CMP, 3,N4-ethano-CMP, and 7-(beta-hydroxy-ethyl)GMP. This would indicate that BCNU generates active two carbon fragments, probably chloroethyl carbonium ions, which are free to react with nucleotides. The production of these substituted bases may be important to the mechanism of action of the therapeutic nitrosoureas since they would probably alter the function of any nucleic acid which contained them.

Prevention of knee instability. Experimental model for prosthetic anterior cruciate ligament

Loss of the anterior cruciate ligament (ACL) in the dog results in a predictable type of arthritis. This condition can be prevented by successful prosthetic substitution of the anterior cruciate ligament (ACL). The condition is a practical model, and a sensitive index of success and failure for evaluation of prototype prostheses. Changes in the joint can be differentiated on the basis of cruciate insufficiency and reaction to the synthetic implant. The model was defined by replacing the ACL with a mesh or tape Dacron prosthesis in 16 Beagle dogs. Gait and anterior drawer sign are unreliable parameters of ACL insufficiency in dogs. At sacrifice up to 3 years postoperatively, 8 joints out of 32 joints were without arthritic changes. Arthritis developed in all joints in which the prosthesis elongated or broke. Failure always occurred intra-articularly at the mouth of a bone tunnel. Successes were inconsistent even with a single material and animal breed. The drillhole techniques used in ACL reconstructions are difficult to standardize. Variability in placement of the prosthesis is compounded by cutting action of bone edges. Porous mesh did not provide a lattice for true ligament regeneration through the joint. Fixation was not a problem in this series.

Improvement in the results of treatment of osteogenic sarcoma

Experience with 70 patients having osteogenic sarcomas treated between 1968 and 1973 demonstrated the importance of persistence in the management of the disease of these patients. Resection for pulmonary metastases in one or both lungs, often on more than one occasion, will salvage a number of these patients, thus improving the cure rate. Adriamycin has proved an effective palliative agent and a useful adjuvant to surgical therapy. Although the cure rate of tumors arising distal to the knee is much higher than that of more proximally situated tumors, resection of osteogenic sarcomas of the distal part of the femur does not require removal of the entire femur when care is taken to resect well above the site of the apparent tumor. Some osteogenic sarcomas are sensitive to adequate dosages of radiation therapy, but the exact role of this method is yet to be determined. No definite beneficial result could be attributed to any of a variety of modalities of immune stimulation therapy.

Minimizing radiation exposure in dental radiology

Rectangular field collimation gives high quality roentgenograms and reduces unnecessary exposure of radiation to the patient by 73-96 per cent.