Interaction of selectively spin-labeled 70S ribosomes with tRNAPhe. An electron paramagnetic resonance study

70S ribosomes from Escherichia coli, selectively spin labeled on the SH groups of proteins S18, S12, S21, S17, and L27, were used to study the formation of the tertiary complex ribosome-poly(U)-tRNAPhe. Most of these ribosomal proteins are located in the region of binding of tRNA. The electron paramagnetic resonance observable structural change suggests a loosening of the ribosome structure upon binding of the tRNA molecule.

A comparative study of flap survival rates in end-to-end and end-to-side microvascular anastomosis

This study compared free flap survival rates following end-to-end and end-to-side arterial anastomoses. A groin flap was transferred to the anterior cervical region in 40 rats. There were 20 rats in each experimental group. The end-to-side group was further divided into subgroups depending on the angle of the anastomosis, which was either 60 degrees or 90 degrees. The results revealed no significant difference in the survival rates between any of the groups (which varied between 80 and 85 percent). A discussion of previous experimental work and the significance of these results has been presented. The advantages and disadvantages of end-to-side anastomoses have also been discussed.

Interaction of 70 S ribosomes from Escherichia coli with spin-labeled N-Cbz-Phe-tRNAPhe. An electron paramagnetic resonance study

Two selectively spin-labeled Cbz-Phe-tRNAsPhe, one at position s4U8 and the other at position U33, have been used to study the dynamics of tRNA-ribosome interaction in the presence of poly(U) and factors washable from ribosomes. Upon binding to the ribosome, the correlation time of the spin label at position s4U8 decreases markedly while the same parameter for the label in the anticodon increases. The presence of poly(U) is not a prerequisite condition for the EPR spectral changes observed but larger variation occurs in the presence of factors washable from ribosomes. No variation in the correlation time is observed if uncharged spin-labeled tRNAPhe (on the s4U8 residue) is used in these experiments. Most of the ribosome-bound spin-labeled Cbz-Phe-tRNAPhe are puromycin-reactive, and consequently, the observed effect is manifested mainly at the ribosomal P site. These observations seem to suggest that the interaction between the N-blocked aminoacyl residue on the tRNA and the ribosome results in a conformational change on the tRNA, possibly involving tertiary interactions in a region close to s4U8. The role that the amino acid at the 3'-end can possibly play on this structural change is discussed.

Small-Carrion penile prosthesis for the management of diabetic impotence

Of 128 patients who had insertion of a Small-Carrion prosthesis, 36 were diabetic. The insertion of a penile prosthesis in diabetic patients proved to be safe, without increased incidence of infection or rejection of the prosthesis, provided diabetes is under good control before operation. Cystoscopy and cystometrogram are necessary to exclude any possible obstruction or decompensation, thus eliminating potential risk of urinary infection or further decompensation by penile prosthesis. An interval of six weeks after insertion of the prosthesis is needed for resuming sexual activity.

Selective spin-labeling of the ribosomal proteins of 70S ribosomes from Escherichia coli

We have used a series of N-(1-oxyl-2,2,5,5-tetramethyl-3-pyrrolidinyl) maleimide spin labels of different length to label, covalently and selectively, the most reactive sulfhydryl groups of 70S ribosomal proteins of Escherichia coli. Under short periods of labeling (1--2 min), less than two spin labels per ribosome are incorporated and were shown to be distributed mainly on five ribosomal proteins in the following order: S18 greater than S21, L27 greater than S17, and S12. With a long period of labeling (3 h) up to 13 spin labels are attached to the ribosome, and protein S1 is the most labeled. The shape of the electron paramagnetic resonance (epr) signal shows two components with a predominance for the strongly immobilized orientation, and the percentage of these components in each spectra has been evaluated. When the distance between the nitroxide group and the maleimide-attaching group exceeds 6 A (1 A = 0.1 nm) the strongly immobilized orientation disappears. The effect of magnesium ions on these selectively spinlabeled ribosomes shows that the dissociation into subunits does not affect the epr signal, but more spin labels are incorporated into the subunits if labeling is performed under conditions of dissociation.

Intracranial venous thrombosis in young women

Twenty women of child-bearing age with intracranial venous thrombosis are reported. Thirteen developed thrombosis post-partum; 6 while on oral contraceptives. In one patient no cause was found. All diagnoses were confirmed by carotid angiography and in 10 out of 14 patients laboratory data indicated a hypercoagulable state. Coagulation studies were performed in 14 normal puerperal women, matched by age, who served as controls. No statistical differences was found between thrombotic and control groups. Radiologic signs of sino-venous occlusion are reviewed. Conservative treatment with anti-edematous agents, anticonvulsants and antiplatelet aggregants is advocated.

Open diagnostic peritoneal lavage in blunt trauma victims

Open diagnostic peritoneal lavage was 97.8 per cent accurate for diagnosis of intra-abdominal injury in 2,072 blunt trauma victims. The only significant injuries missed were in certain patients with a ruptured hemidiaphragm, renal trauma and extraperitoneal bladder rupture. However, these injuries were identified by other means. False-postive lavage results are generally a consequence of technical error and can be minimized by careful surgical technique. Hemoperitoneum must be explained for all patients to prevent needless morbidity and mortality. Only diagnostic tests of proved value in blunt abdominal trauma should be used and risk to the patient must be minimized. We currently rely upon diagnostic laparotomy to evaluate hemoperitoneum in patients with a weakly positive lavage result confirmed by a second infusion. With this policy, approximately one of every four to five laparotomies was for injuries not requiring surgical therapy; and, the over-all morbidity rate and mortality was 12 and 3.5 per cent, respectively, in this group. By using open diagnostic peritoneal lavage in essentially all blunt trauma victims, we have had no deaths from either unrecognized intra-abdominal injury or delayed treatment.

[Evaluation of the experience of the observer in the interpretation of myocardial scintillography with radioactive phosphates]

Two-hundred-and five myocardial scans with radioactive phosphates, performed in 185 patients interned at the Coronary Care Unit due to acute chest pain (147 myocardial infarcts: 58 coronary heart disease), were independently interpreted by six observers with different degrees of experience on the lectures of these kind of images (two nuclear physicians, two cardiologists, and two fellows of the Nuclear Medicine Unit). A series of six different grades of myocardial concentration of the radioactive phosphates, related to its osseous concentration were followed. Each observer reported the grade of concentration he found in each image. The fraction of myocardial infarcts and of coronary heart disease found by each observer in every grade of concentration were calculated. With these data, it was determined the optimal criterion level of each observer by which he attained the minor incidence of false negative and false positive results. Four observers found their optimal criterion level on 2F, where grades 0-2D are considered as negative, and grades 2F-4 are considered as positive. One observer found his optimal level at 2D (0-1: -; 2D-4: +) and other at 1 (0: -; 1-4: +. By using a decision matrix which relates results of the test with a binary outcome (normal, abnormal) to the actual diagnosis, also with a binary outcome (infarct, no infarct), the ratios for "sensitivity", "specificity" and "accuracy" were derived for each observer performing at his particular optimal criterion level. Our results suggests that the observer performance depends on his particular degree of experience in interpreting nuclear medical images and on his visual perception. It was concluded that it is necessary to periodically evaluate the individual optimal criterion level of the physicians in charge of the lectures of the myocardial images with radioactive phosphates, liable to shift with time in relation to the experience of the observer. The need of a more objective procedure to quantitate myocardial concentration of the radioactive phosphates is also implied.

Transcatheter embolization of autologous clot in the management of bleeding associated with fractures of the pelvis

Extraperitoneal hemorrhage, associated with a fracture of the pelvis, is a major cause of death in pedestrian accidents. Transfusion alone may be unsatisfactory. Direct control of bleeding may be required. Surgically, this may be technically difficult or inadequate. Transcatheter embolization of autologous clot was used to control hemorrhage in three patients with such a fracture. If laparotomy is required immediately, arteriography of the pelvic area may be done postoperatively, If laparotomy is not performed, arteriography may define pelvic bleeding sites. Transcatheter embolization of autologous clot controls hemorrhage from branches of the hypogastric artery.

Characterization of T4 mutants that partially suppress the inability of T4rII to grow in Lambda lysogens

In the course of isolating viable T4 deletions that affect plaque morphology (HOMYK and WEIL 1974), two closely linked point mutant, sip1 and sip2, were obtained. They map between genes t and 52, cause a reduction in plaque size and burst size, and partially suppress the lethality of rII mutants for growth in lambda lysogens. The characteristics demonstrate that sip1 and sip2 are similar to mutants previously reported by FREEDMAN and BRENNER(1972). In addition, D. Hall (personal communication) has shown that sip1 and sip2 are similar to the mutant farP85, which affects the regulation of a number of early genes (Chace and Hall 1975).--Sip suppression of rII mutants can be demonstrated in one-step growth experiments, even when both rII genes are completely deleted. This indicates that sip mutants do not simply reduce the level of rII gene products required for growth in a lambda lysogen. Instead, they alter the growth cycle so as to partially circumvent the need for any rII products.--Mutations at two other sites, designated L1 and L2, reverse the poor phage growth caused by sip and, in the one case tested, reverse the rII-suppressing ability of sip.

Ethylenimine-inactivated rabies vaccine of tissue culture origin

The replication of seven rabies virus strains (CVS, HEP, PV, ERA, WIRAB, CPZ and BOLIVAR) in BHK cells and the inactivation dynamics of these strains by beta-propiolactone, acetylethylenimine, and ethylenimine were studied to find the most immunogenic strain and the most economic and stable inactivating agent for the production of an inactivated tissue culture rabies vaccine for animal use. The seven strains reached the peak of virus production 3 to 5 days after inoculation of the cell culture; PV yielded the highest virus titer (10(9) plaque-forming units/ml). The infectivity of virus suspensions containing 10(7) to 10(8) plaque-forming units/0.1 ml was inactivated by beta-propiolactone in 0.5 h, acetylethylenimine in 3.0 h, and ethylenimine in 1.0 h. Most of the vaccine lots prepared with the different strains and inactivating agents passed a modified National Institutes of Health potency test. The vaccines prepared with the PV strain had consistently higher antigenic values (equal or better than four) than the other six strains. This difference was highly significant (F6,12=59.8), whereas there were no statistically significant differences among the antigenic values of the vaccine lots prepared with the three inactivating agents. Batches of lyophilized and liquid vaccine stored at 4 C maintained potency for over 1 year. Ten dogs vaccinated with a vaccine prepared with the PV strain and inactivated with ethylenimine developed a good antibody response and resisted challenge 60 days after vaccination, while seven of eight nonvaccinated controls died of rabies. This information indicates that an inactivated, stable, economic, and easy-to-prepare rabies vaccine can be produced in BHK cells by using the PV strain and ethylenimine as an inactivating agent.

Letter: International documentation service on stress

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