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.

'Antigenic' disparity between leukaemic lymphoblasts and normal lymphocytes in identical twins

Circulating lymphocytes of a normal boy were unequivocally stimulated by irradiated leukaemic lymphoblasts from his identical twin with acute lymphoblastic leukaemia. This reaction indicates that there is an `antigenic' disparity between these two types of cells. It is possible that leukaemic cells may acquire new surface antigens or that existing surface antigens of lymphoid cells may be modified during the process of leukaemogenesis.

Isoelectric fractionation and some properties of a protease from soyabean seeds

A protease, capable of hydrolysing benzoyl DL‐arginine p‐nitroanilide(BAPA), and L‐amino acid β‐naphthylamide derivatives, was purified, by isoelectric focusing in the region pH 3–6, from dormant and 6‐day germinated soyabean seeds. The enzyme was focused at pH 4·80. The Km value using BAPA as substrate was found to be 5·03 × 10−4M. Maximum activity of the enzyme towards BAPA was obtained in the pH 8·2–8–5 region. Slight activation was observed in the presence of 0·05 M concentration of Ca2+ and Mg2+ ions. The protease lacked caseinolytic activity, and was not inhibited by Kunitz soyabean trypsin inhibitor.