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Metal implants are in general not compatible with the tissues of the human body, and in particular, blood exhibits a severe hemostatic response. Herein we present results of a technique to mask the surface of metals with a natural biopolymer, hyaluronan (HA). HA has minimal adverse interactions with blood and other tissues, but attachment of bioactive peptides can promote specific biological interactions. In this study, stainless steel was cleaned and then surface-modified by covalent attachment of an epoxy silane. The epoxy was subsequently converted to an aldehyde functional group and reacted with hyaluronan through an adipic dihydrazide linkage, thus covalently immobilizing the HA onto the steel surface. Fluorescent labeling of the HA showed that the surface had a fairly uniform covering of HA. When human platelet rich plasma was placed on the HA-coated surface, there was no observable adhesion of platelets. HA derivatized with a peptide containing the RGD peptide sequence was also bound to the stainless steel. The RGD-containing peptide was bioactive as exemplified by the attachment and spreading of platelets on this surface. Furthermore, when the RGD peptide was replaced with the nonsense RDG sequence, minimal adhesion of platelets was observed. This type of controlled biological activity on a metal surface has potential for modulating cell growth and cellular interactions with metallic implants, such as vascular stents, orthopedic implants, heart valve cages, and more.

The incorporation of l-lysine-U-C14 into proteins of slices of a number of tissues of the rat has been studied in the presence and absence of glucose under aerobic conditions. The addition of 0.009 m glucose increased the incorporation of radioactive lysine into proteins of slices of rat testis and head of epididymis by 600 and 160%, respectively. Similar additions of glucose caused essentially no change to a 50% enhancement of protein labeling in slices of thymus, spleen, pancreas, tail of epididymis, kidney, brain, diaphragm, heart, liver, seminal vesicle, a number of transplantable rat tumors, and regenerating rat liver. The data obtained indicate that the enzymatic systems involved in the incorporation of labeled lysine into protein of the testis are more sensitive to the addition of exogenous glucose than those of a number of other tissues of the rat.

The incorporation of l-lysine-U-C14 into protein of slices of experimentally induced cryptorchid testes of the rat has been studied at various time periods ranging from 4 to 40 days after abdominal transplantation. Comparisons of protein labeling from radioactive lysine into slices of adult scrotal testes, immature testes, and an interstitial-cell testicular tumor of the mouse have also been carried out. In addition, the effects of temperature and of exogenous glucose on protein labeling of these tissues have been investigated. The data obtained indicate that the incorporation of labeled lysine into protein of slices of cryptorchid testes is markedly greater than that observed for slices of scrotal testes obtained from the same animal. It is suggested that of the various cell types found in the rat testis, the spermatogonia and primary spermatocytes demonstrate the highest degree of protein labeling from radioactive lysine and that the enzymatic systems involved in the incorporation of radioactive lysine into protein of the spermatids display the most susceptibility to elevated temperatures and the greatest sensitivity to the addition of exogenous glucose.

Following oral administration of 300 mg. of methaqualone to 7 subiects there was an average peak plasma level of 3.0 p.g per milliliter in 2 hours. Average plasma half-life was 2.6 hours. Per cent absorption at each time point after administration indicated that 67 per cent absorption occurred in one hour and 99 per cent was absorbed in 2 hours.

{Received 1st March 1965) Summary. Unilateral cryptorchidism has been produced in prepubertal rats by abdominal fixation of an undescended testis and in adult rats by transplantation of a previously descended testis from the scrotal sac into the abdominal cavity. The incorporation of l-lysine-U-14C into protein of slices of both types of experimentally induced cryptorchid testes 30 days following the surgical procedure has been found to be markedly greater than that observed for slices of contralateral, scrotal testes of the same animal. It has long been known that cryptorchidism leads to severe spermatogenic damage. In addition, the undescended testis has been reported to be over thirty times more likely to become malignant as compared to a normal, scrotal testis (Campbell, 1942). For these reasons, our laboratory has initiated studies on the metabolism of mammalian testicular tissue beginning with an investiga¬ tion of the incorporation of 14C-labelled lysine into rat testicular protein. It was initially found that the incorporation of L-lysine-U-14C into protein of slices of cryptorchid testes which were experimentally-induced in adult rats was much greater than that observed for slices of scrotal testes obtained from the same animal (Davis, Morris 8c Hollinger, 1964). The present experiments were designed to explore further this finding, as well as to investigate the physiological significance of inducing cryptorchidism by transplanting a previously descended adult testis from the scrotal sac into the abdominal cavity. Unilateral cryptorchidism was experimentally produced in two groups of male Sprague-Dawley rats. The first group (five animals) consisted of prepubertal rats which were 20 days of age and in which the testes had not yet begun their descent. Abdominal fixation of the undescended testis was carried out by performing a midline abdominal incision under ether anaesthesia and suturing the right testis to the dorsolateral abdominal wall, thereby preventing its normal descent. A fine 6-0 surgical silk suture was passed just under the

A procedure for both a rapid qualitative and a quantitative determination for adenine in a mixture of various purines and pyrimidines is described. In addition, the method can also be applied for the rapid detection and quantitative estimation of a number of adenine nucleosides and nucleotides without prior hydrolysis of these compounds.