The dental externship: an educational methodology for extramural experiences.

Although this pilot program in extramural experiences failed to confront any major injustices of the health care system, the establishment of the externship succeeded in filling a major gap in the present curriculum. The selected sites afforded students the experience of relating to psychiatric patients, institutional bureaucracy, and incarcerated populations. Social attitudes appeared modified as a consequence of the externship, and a commitment to improve the delivery system was made.


Six-month and one-year clinical evaluation of a composite resin for class II restorations.

This clinical study was undertaken to compare a composite resin, containing a modified filler, with a dental amalgam alloy in Class II restorations. Eight senior dental students placed 98 pairs of restoration in 69 patients. After six months and one-year, 69 pairs of restorations in 49 patients were evaluated by two examiners. No significant differences were found between baseline and one-year evaluations for ratings of anatomic form and marginal adaptation. Color match was found to decrease in time, and marginal discoloration was found to increase in time. Failures of restoration were not attributed to the materials, but more probably were caused by faulty cavity preparations. Although the results for each patient analysis indicated no significant differences in anatomic form and marginal adaptation at one year, the B ratings for these two criteria for both types of restorations in this study indicate the need for continued clinical evaluation. The decreased number of composite restorations with good color match is not unexpected and indicates the need for judgment when selecting composite resin as the restorative material in Class II preparations for esthetic purposes. The significant number of composite restoration in this study with increasing marginal discoloration is reason for concern and continued evaluation of these restorations. Marginal discoloration and poor marginal adaptation are factors related to recurrent caries and replacement of restorations. Thus, continued research and clinical evaluation of new restorative materials is a necessity.


Preventive dentistry in private practice: a survey in Kentucky.

General practitioners in Kentucky were surveyed to establish a profile of preventive practice in the state and to identify factors influencing the profile. Both questionnaire and interview methods were used. A Kentuckian has a 55% chance of seeing a dentist who advises all his patients about prevention, and an 87% chance of seeing one who adivses some of his patients. Persons between the ages of 6 and 24 are most likely to receive preventive services. The dentist is selective about who receives a preventive-oriented examination, and he is more likely to perform the services than auxillaries. The profile shows the need for a greatly increased emphasis on preventive dentistry in undergraduate and continuing education courses and for the increased use of auxiliary personnel in the delivery of preventive services.


Electromygraphic biofeedback and tricyclic antidepressants in myofascial pain-dysfunction syndrome: psychological predictors of outcome.

Training in muscle relaxation using electromyographic biofeedback was successful in relieving myofascial pain-dysfunction symptoms in 15 of 23 patients. Half of the remainder were helped by tricyclic antidepressants. Effects of the therapies corresponded to psychological factors assessed before treatment. The implications of these factors are discussed.


The influence of proximal retention grooves on the retention and resistance of class II preparations for amalgams.

The addition of proximal retention grooves to various designs of the Class II cavity preparation considerably improves the retention and resistance characteristics of amalgam restorations. The incorporation of proximal grooves should reduce the necessity for gross outline form as a means of gaining adequate retention adn resistance in the Class II preparation.


Brain damage after intrathecal methotrexate.

Ten brains from leukaemic patients given intrathecal methotrexate and 10 from leukaemic patients without intrathecal therapy have been examined. Three of the methodtrexate treated patients appear to have died from their therapy. The histological changes consisted of destruction of oligodendrocytes, sometimes complete over large areas, and sometimes relatively slight. All the patients who survived long enough after treatment showed severe astrocytosis.


Survey of local anesthetic toxicity in the families of patients with atypical plasma cholinesterase.

There have been reports of toxic reactions to ester-type local anesthetics in patients with genetic anomalies of plasma cholinesterase in so-called dibucaine-resistant homozygotes or heterozygotes. Because of these reports, 23 patients with prolonged apnea after administration of succinylcholine were studied with Kalow's method for abnormal dibucaine number (DN), which characterizes this condition, and for the history of local anesthetic toxicity. Thirty-eight relatives of abnormal individuals were studied in the same manner. Two atypical dibucaine-resistant homozygotes and the relative of one of these had toxic reactions to ester-type local anesthetics. Although low doses of ester-type local anesthetics may be tolerated by atypical homozygotes, these agents are best avoided and amide-type local anesthetics or tetracaine, which is hydrolyzed at a normal rate, should be used. Individuals with atypical plasma cholinesterase should wear a Medic-Alert bracelet or amulet so that complications and fatalities can be avoided.


The combined anterior and posterior maxillary ostectomy: a new technique.

We have used the combined simultaneous anterior and posterior maxillary ostectomy to correct 32 dentofacial deformities during the past five years. Alterations and improvements in the procedure advocated by us in 1969 have made it more versatile. In indicated cases, it provides the best method to obtain optimum esthetic and functional results. In our experience, this approach permits a direct and definitive method for the correction of a group of dentofacial deformities that have been previously approached less directly with resulting compromised functional and esthetic results. The indications, methods of treatment, and follow-up data of this procedure are presented with two illustrative cases.


Juvenile hemangioendothelioma: report of a case and review of the literature.

A solitary juvenile hemangioendothelioma on the maxillary gingiva of a newborn white male has been presented. No recurrence or evidence of systemic involvement has been noted in the 18 months following excision. The literature was reviewed with emphasis on the varying location and behavior of the lesion and the methods of treatment. Simple excision of the isolated, histologically benign neoplasm is recommended provided adequate follow-up is assured.


Soft tissue closure of unilateral congenital maxillary alveolar cleft.

A surgical procedure for the soft tissue closure of a congenital maxillary osseous and soft tissue cleft is presented. Normal function is established and prosthodontic replacement of congenital dental defects is facilitated.


An appliance that permits early mobilization after correction of mandibular prognathism.

With certain orthognathic surgery patients, such as epileptics, severe asthmatics, or those with other medical problems that increase risk during intermaxillary fixation, there occasionally may be an indication for a reduced fixation time. By using Vitallium mesh for stability, immobilization for 2 to 2 1/2 weeks has proved to be sufficient in a limited number of cases. Mobilization before two weeks has not been attempted. The procedure, however, is not recommended as a routine method of fixation.


The effects of exchange transfusion on intracranial pressure in patients with Reye syndrome.

Intracranial pressure has been monitored in ten patients with Reye syndrome. All of the patients were comatose and all were treated with dexamethasone, mannitol, hyperventilation, and multiple exchange transfusions. Five of these children are alive and well; five died. In each case ICP monitoring allowed for immediate treatment and evaluation of the mode of therapy used to reduce elevated ICP. Exchange transfusions in all patients either reduced the increased ICP or made the pressure rises easier to manage. ICP is not always reflected by lumbar spinal fluid pressure or clinical state. In our hands, ICP monitoring has proved to be a safe technique for the investigation of the significance of raised ICP in the outcome of patients with Reye syndrome and of the effectiveness of a chosen therapy in reducing this pressure.


Clinical comparison of the free soft tissue autograft and partial thickness apically positioned flap--preoperative gingival or mucosal margins.

Apically positioned split thickness flaps were performed at two selected sites in each of 10 patients. Equivalent amounts of periosteum were left exposed to standardize the method. In five patients the preoperative dentogingival margins consisted of gingiva, whereas in the five others a margin of alveolar mucosa was present. In all patients the pre-existing margin was sutured apically to periosteum, after reflection of the split thickness flap. At one surgical site in each patient a free soft tissue autograft, donated from the palate, was sutured to the periosteum left exposed coronal to the apically positioned flap margin. The second surgical site was left not covered by any biological dressing. Measurements from three fixed reference points on a stable acrylic device were recorded preoperatively and at 2, 4, 6, 8 and 12 weeks postoperatively. The graft and split thickness flap procedures were then biometrically compared by application of the Null Hypothesis and t test for the difference of the means to determine any significant differences. It was concluded that the presence of a preoperative dentogingival margin of gingiva suggested that either the free graft or split flap procedure would eliminate pockets extending beyond the mucogingival junction, and would establish adequate zones of attached gingiva without deformity at the dentogingival junction. However, the presence of a preoperative margin of alveolar mucosa suggested the use of the free soft tissue autograft to attain the above. The thickness of connective tissue afforded by a preoperative margin of gingiva was assumed to be the responsible factor for the above conclusions.


An evaluation of clinical tooth mobility measurements.

This study evaluated the reliability and reproducibility of the modified Miller Index of horizontal tooth mobility. Each of three periodontists utilizing the modified Miller Index assessed the horizontal tooth mobility of 50 teeth in five subjects. The same teeth were also evaluated by the periodontometer. The results of these two methods were then compared. It was found that: (1) there were a high positive correlation between the periodontists' (pooled) assessment of clinical tooth mobility and the measurements of the periodontometer, (2) in any given patient the three periodontists (pooled) were highly accurate in their ability to rank teeth in order of their mobility as determined by the periodontometer, and (3) the periodontists (individually) were not as consistent when comparing teeth with the Miller Index across different subjects. The periodontists did not accurately utilize the Miller Index as it was originally described. It appears that the periodontists either ignored the reference to 1 mm in the description of the Miller Index, or they were unable to estimate what constitutes 1 mm of movemnet in the mouth. The periodontists all consistently scored as a 2 degrees mobility a tooth that moved approximately 0.5 mm not 1.0 mm as described by Miller. It is suggested that the modified Miller Index as described here provides an efficacious system for evaluating horizontal tooth mobility. It provides accurate, reproducible mobility scores in clinical studies requiring an estimation of this parameter. However, for individual teeth, when the clinician or researcher is trying to evaluate the effects of therapy on the periodontium and relatively few evaluation are made, the modified Miller Index may not provide the required degree of sensitively.


Some anatomical factors related to furcation involvements.

A total of 305 dry human skull specimens were examined for the presence of furcation involvements. Of a total of 188 furcation involvements, 142 (75%) were related to the close proximity of the furcation to the cemento enamel junction of the tooth.


Ultrastructural gingival reactions to gold foil restorations.

In the case of class-V gold foil restorations prepared below the gingival sulcus in beagle dogs after elevation of a flap, chronic inflammatory changes were observed after 3 weeks in the adjacent epithelium and connective tissue of the gingiva with the presence of dental plaque between the gold restorations and sulcular epithelium. However no inflammation was observed in the junctional epithelium and the subjacent connective tissue 3 weeks after implantation of a gold strip burnished and bounded to the root surface after elevation of a flap. The cell membranes of the superficial epithelial cells were either directly applied to the gold surface or were separated from the latter by an extracellular space about 200 to 500 A in width. No hemidesmosomes were seen. The different responses noted in the two experiments are related to the presence or absence of dental plaque and probably to the surface difference of the gold restorations.


Effect of tongue brushing on formation of dental plaque.

The effect of tongue brushing on formation of dental plaque was studied in two groups of dental hygiene students. In one of the groups plaque formation during a 4-day period of no oral hygiene procedures was compared to a 4-day period of tongue brushing as the only hygiene procedure. In the other group tongue brushing as an adjunct to tooth brushing was evaluated on plaque formation during 7-day periods of partially ineffective tooth brushing. Both experiments failed to show any effect of the tongue brushing on plaque formation.


In vitro attachment of human gingival fibroblasts to root surfaces.

Human gingival fibroblasts were used to study the in vitro attachment of cells to the root surface of periodontally-involved teeth. The portion of the root exposed to the disease process had little or no cell attachment; on the remainder of the root, the cells attached normally. Prior extraction of the roots with phenol-water or the mechanical removal of diseased cementum allowed the cells to attach normally. All things being equal, the extrapolation of these data to an in vivo situation dictates that a clinical success would depend upon complete removal of toxic materials from diseased cementum or the removal of the cementum itself.


New method of viewing root surfaces.

A new technique, density slicing and color coding, was utilized in examining root surfaces. This technique proved to be an adjunct in evaluating tooth surfaces and appeared to have future dental application. Density slicing and color coding vividly portrays the root surface, the depth of depressions and the concentration and flow pattern of calculus, enhancing the ability of the naked eye to visualize root surface topography.


Relations between early dental calculus production and calcium and phosphate parameters of salivary fractions.

A pilot study was carried out to obtain an idea of the strength of the relations between early mandibular calculus production in humans and amounts and concentrations of bound calcium and phosphate in three salivary fractions. The salivary fractions were: (1) the spontaneous precipitate from incubated whole saliva, (2) the spontaneous precipitate from incubated centrifugal (20,000 X g) saliva supernatant and (3) the fresh centrifugal saliva sediment. Strong and highly significant correlations were found for the amount and concentration of calcium in the fresh sediment and whole saliva precipitate fractions. Although the correlations for the calcium parameters of the saliva supernatant precipitate were not significant, there were significant differences in these parameters between low and high calculus formers as determined by Student's t test. Relations between calculus production and amount and concentration of phosphate were weaker and not significant for all fractions. The data suggest that the amount or concentration of calcium in fresh saliva sediment is an important determinant of early mandibular calculus production.


The effect of 2-deoxy-D-glucose and D-glucose on the efferent discharge rate of sympathetic nerves.

Efferent discharges were recorded from nerve filaments dissected from the adrenal and renal nerves in the rabbit. 2. An increase in discharge rate was observed in the adrenal nerve filaments following I.V. administration of 2-deoxy-D-glucose (2-DG). No change in discharge rate after 2-DG infusion was observed in the renal nerve filaments. 3. A decrease in discharge rate of the adrenal nerve filaments was observed after I.V. injection of glucose, but there was no change in the activity of renal nerve filaments. 4. Transection of the spinal cord abolished the adrenal nerve response to the systemic administration of 2-DG and glucose. 5. It is suggested that there might be a pathway from the hypothalmic area to the adrenal nerve cells of the spinal cord, but not to the renal nerve cells, through which activity of the adrenal nerve might be changed in response to 2-DG and glucose infusion.


The cast restoration--why is it high?

Two clinical variables previously cited in the literature have been related to inaccuracies inherent in some indirect quadrant and full dental arch techniques. The Coe checkbite tray system appears to control these clinical variables better than any other procedure presently in use. No attempt has been made to correlate concepts discussed herein with restorative Types II and III which require more sophisticated procedures. The choice of any technique must be based upon intelligent gathering of pertinent facts of clinical history, examination procedures, diagnosis, and treatment planning.


A simple test to determine the need for occlusal treatment.

This report has described simple confirmation tests which show the direct relationship between a patient's occlusal interferences and his neuromuscular or temporomandibular articulation dysfunction. These tests are simple to perform, take only a few minutes, and aid in confirming the need for occlusal therapy.


Psychological considerations in maxillofacial prosthetics.

An attempt has been made to integrate information from psychological principles and clinical research which is relevant to maxillofacial prosthetics. Attention was given to the role of body parts in the human experience, with particular consideration of facial aspects. The importance of the maxillofacial region in early development, personality dynamics, and day-to-day interpersonal relationships was reviewed together with several specific problems which often accompany maxillofacial changes in structure or function. The dentist must be concerned with the patient's expectations, personality characteristics, and ability to accept and integrate the prosthesis. Several implications for clinical practice were presented. The dentist's understanding and utilization of psychological considerations should result in increased effectiveness in treatment and rehabilitation of maxillofacial patients.


Physical problems in obtaining records of the maxillofacial patient.

The maxillofacial prosthodontist has the dilemma of obtaining jaw relation records with structures that have been altered anatomically and/or physiologically. In the maxillae, problems associated with stability of the recording base require the prosthodontist to equalize pressure as best he can in obtaining jaw records. The maxillofacial prosthodontist is faced with the additional problem of altered mandibular movements. Five patients with lateral resections of the mandible were tested in a pilot study. These patients could not make protrusive or repeatable lateral movements. Anatomic correlations, especially the unilateral action of the mylohyoid muscle, may account for this pattern of abnormal mandibular movements. This study will continue.


The value of the nose width as an esthetic guide in prosthodontics.

A radiographic method was used to measure the interalar and interalar-fold widths of the nose on 80 men and women. These distances were compared to the subjects' intercanine distances as measure on artificial stone casts. In 56 of the subjects, the width of the skeletal nasal aperture was measured and compared to the intercanine distance. From the results of this study, the following conclusions can be drawn. 1. There was no significant relationship between the intercanine distance and the interalar width of the nose in the 80 men and women who served as subjects in this study. 2. There was no significant relationship between the intercanine distance and the interalar-fold width of the nose in the 80 men and women in this study. 3. The presence or absence of a significant relationship between the intercanine distance and the width of the skeletal nasal aperture was not demonstrated conclusively in this study. 4. The results of this study show that the width of the nose would not be a reliable guide for selecting or arranging artificial anterior teeth, provided one concurs that they should be the same size and shape and occupy the same position as their natural predecessors.


Mouth protector for an edentulous patient.

Upper and lower bases and occlusion rims are made of a soft vinyl plastic to form a mouth protector for an edentulous patient. In practical use, the patient can breathe more comfortably with the protectors in place (Fig. 4) than with dentures in the mouth. In addition, the prosthesis is an aid in the prevention of injury to the jaws and head.


An oral hygiene measurement system for possible research and clinical use.

A new hygiene index has been developed that it is felt better meets the requirements for individual patient analysis than other indices. Examiner subjectivity is reduced by scoring tooth surfaces as clean (0) or dirty (1), determining a percentage of "dirty" surfaces which then becomes the Hygiene Analysis Index. Tested on a group of dental students it appears to discriminate adequately between the various levels of mouth hygiene.


Comparative toothbrush efficiency utilizing a new oral hygiene index.

Through the use of a newly developed Hygiene Analysis Index (HAI), nine toothbrushes were evaluated for plaque-removing efficiency in 11 dental students. Results indicate that brush selection is an individual matter with no one brush clearly superior to all others. Further study is necessary before definite conclusions can be made.


Comparisons of poverty and nonpoverty groups on dental status, needs, and practices.

Poverty and nonpoverty adults have been screened in a program of Multiphasic Health Testing in which dental examinations were provided and in which information on dental care behavior was obtained through a health inventory using a video-terminal for recording replies. Findings of the dental examination indicate that, whatever measure of oral health was used, oral health of the poverty group was poorer than that of the nonpoverty group. The poverty group, for example, had more dental problems, and the problems they had were more severe. They also had lower levels of oral hygiene and less restorative treatment. The poverty group also was more likely to be edentulous, and to have higher levels of untreated decay and periodontal diseases. They had more missing teeth, and fewer restored teeth. Nearly all poverty-nonpoverty differences persisted when the data were controlled for age and sex. Information from the health inventory indicates that the poverty group is less likely than those in the nonpoverty group to seek dental care in general, and also specifically for rreventive dental services. Even among the nonpoverty group, however, one third stated that they never sought dental care for "cleanings or checkups." Daily toothbrushing, on the other hand, was generally reported by both poverty-status groups. Consistent relations were found between oral health practices and oral health in both poverty and nonpoverty groups...


An evaluation of the University of Minnesota summer rural dental externship program.

This paper has presented an initial attempt at evaluating the influences and procedures of a specific health personnel-oriented program. It would seem legitimate to be concerned that many programs do not provide for systematic evaluation. If funds are to be directed to support the most effective strategies in the area of health manpower service and research, it seems imperative that systematic information be available for decisions concerning overall program effectiveness as well as program components. The Summer Rural Dental Externship Program evaluated here was found to be generally effective and will likely improve as a result of data provided by the evaluation. It is hoped that the methodology presented might have some general applicability and give some initial direction to those with similar interests and concerns.


Induction of follicular growth, ovulation and luteinization in the human ovary.

Studies on human ovulation are described, in which follicular growth and ovulation were controlled by HMG, clomiphene and HCG. Three regimes of treatment were employed: several injections of HMG, followed by an injection of HCG, a course of clomiphene followed by an injection of HCG and an injection of HCG alone timed to just pre-date the surge of  LH during the natural cycle. Aspects of follicular growth and the timing of ovulation have been studied following the use of these treatments. Follicles rupture some 37 hr after the injection of HCG in cycles where HMG or clomiphene were used to stimulate follicular growth. The timing of ovulation was established with less precision when HCG was used to induce ovulation in the natural cycle, since the LH surge sometimes occurred before HCG was injected and other problems arose during luteinization. The numbers of follicles growing in response to stimulation with clomiphene or HMG showed only a slight relationship to the levels of oestrogen excreted in urine. The morphology of the preovulatory follicle was noted and some biochemical and physiological parameters were measured, including the levels of various steroids and prostaglandins in follicular fluid. The morphology of the oocyte and granulosa cells was recorded. These observations are discussed in relation to several physiological and clinical aspects of ovarian activity: the regulation of follicular growth, the timing of ovulation following the LH surge, factors affecting ovulation, and the relation of studies on follicular growth and ovulation to the rhythm method of contraception and other medical situations.


The rhythm method of contraception.

The rhythm method (safe period) is the only contraceptive method which is approved and actively promoted by the Roman Catholic Church. It therefore holds and attraction to a large number of followers. This paper reviews the historical development of the method from the initial efforts in the nineteenth century to the work of Ogino and Knaus, and covers the variations which are based on alteration of the basal body temperature and changes in cervical mucus. Although this method should be devoid of side effects, certain risks have been reported due to the possible fertilization of an overripe ovum. There may also be a higher risk of ectopic pregnancy than normal to users of this method and these reports are reviewed. The results of field trials concerning the use effectiveness of the method are also examined.


Sjögren's syndrome terminating as a myeloproliferative disorder.

A 59 year old female was diagnosed as having Sjögren's syndrome in 1963. A short time later, she developed a refractory sideroblastic anemia. In 1972, she was found to have a preleukemic state with a persistent "shift to the left" of the granulocytic series, terminating early in 1974 as acute myeloblastic leukemia. Although several cases of malignant lymphomata have been described in association with Sjörgen's syndrome, to our knowledge no other example of Sjörgen's syndrome has been described in association with a myeloproliferative disorder. Defective immune surveillance produced by the Sjörgen's syndrome may have permitted the development of the myeloproliferative syndrome. Alternatively, both disorders may have developed from a hemopoietic stem cell defect.


Cytogenetic basis of acute myeloid leukemia.

The chromosomes of 12 adult patients with acute leukemia were analyzed by conventional means and by Giemsa and centromeric banding techniques. Acute myeloblastic leukemia was diagnosed in 7, acute myelomonocytic leukemia in 2, and acute undifferentiated leukemia in 3. Bone marrow was aspirated from patients when in relapse or remission, and both euploid and aneuploid cells were examined. All patients showed trisomy no. 9 and many showed additional numerical or structural changes in some or all their cells. These changes included monosomy no. 21 and/or monosomy no. 8. The proportion of trisomy no. 9 cells was 30-50% in patients in full remission and up to 100% in patients in relapse; thus trisomy no. 9 might be an important marker of leukemic cells. A mechanism was proposed to explain the induction and selection of the trisomy no. 9 karotype.


[One year's experience with mechanical ventilation in newborn infants (author's transl)].

During the first year of newborn intensive care at the Landeskinderkrankenhaus Linz/Donau there were 80 cases of artificial ventilation, 62 of these were Low Birth Weight Infants (LBWI). 12% of all LBWI required mechanical ventilation. 53 ventilated infants suffered from severe Hyalin Membrane Syndrome (HMS). 17 survived, 18 died of intraventricular hemorrhage and 18 died of HMS. Bronchopulmonary Dysplasia was found in all patients ventilated for more than 7 days. 5 cases of pneumothorax occurred during ventilation. Good results were obtained in cases of respiratory insufficiency other than HMS (15 cases, 12 survivors. Mortality rate of LBWI delivered in Hospitals was 9.9%, whereas 34% of the LBWI delivered at home but cared for under identical conditions in the nursery died. This difference offers good evidence for the importance of the quality of the obstetrical care for the results of newborn intensive care.


[Recurrence of rectal cancer (author's transl)].

36 cases of recurrent rectal cancer are reported. There is a wide-spread spectrum in the appearance of the relapse. Indirect symptoms are dominating. The most frequent of them are caused by obstruction of the bowl or the urinary pathways and by irritation of (lumbo-) sacral nerves. Especially rare manifestations are stressed. Often they are hardly regarded early symptoms of the recurrent cancer. Curative therapy was made 5-times by amputation, 2-times by resection of an anastomosial recurrence. 3 of these patients reach a survival rate over 18 months until now. An isolated pulmonary late-metastasis was removed by lobectomy; this patients shows no recurrence for the last 3 years. Palliative procedures took place in 20 patients. The worth of radiation therapy is to be seen in a (temporary) reduction of pain. Chordotomy remains as ultima ratio for uninfluencable pain.


Analysis of human mandibular movement.

The parametric electrical outputs of the six-transducer mandibulograph were used to analyze three-dimensional pathways, displacement profiles, and velocity profiles of selected mandibular areas during jaw movement. This was accomplished by means of digital computer implementation of derived mathematical equations of motion. Five jaw movements were studied: chewing, open-close, right lateral, left lateral and protrusive. The results demonstrate the analytical and diagnostic value of this method and provice new clarification and insight into the nature of mandibular movements. The following observations summarize the principal findings derived from the analysis of jaw movement patterns of a normal patient. The chewing jaw movement exhibited a smoothly coordinated sequence of events. Lateral jaw motion appeared to be prominent during the masticatory phase and throughout the movement cycle. Mastication was abruptly terminated by a vertical desscent of the mandible through the freeway space, until the condyles began their forward movement producing a rotation in the sagittal plane. T occlusal area continued its downward descent along a nearly vertical pathway producing a compressed figure eight pattern in the frontal plane. The open-close jaw movement exhibited minor periods of hesitancy. Jaw movement was initiated with a forward and downward movement of the condyle occurring at the same time as a downward and backward movement of the occlusal area. This motion produced a rotation in the sagittal plane about a moving axis which was not coincident with the intercondylar axis.  The general form of the command open-close jaw movement was that of noncoincident curved pathways in the sagittal plane with little lateral displacement. Closing jaw movement occurred with the condyle in a protruded position...


Obesity in a New Zealand community.

A retrospective analysis of the height, weight and certain biochemical data from the Rangiora Diabetic Survey is presented. In this survey 93 percent of the 2670 adult Europeans in Rangiora were studied. A high prevalence of obesity was found with 31 percent of the men and 46 percent of the women being greater than 20 percent above their ideal body weight. More than half the women aged 50 years and over were obese by the criteria used. The peak prevalence of obesity was in the seventh decade for women and in the eighth and ninth decades for men. There were significant increases in serum uric acid in obese men and women in each age decade. A surprise finding in the obese men was the increase in plasma protein levels but this did not occur in the obese women. Both men and women had a trend towards higher blood sugars when obese.


The 1968 New Zealand cases of primary amoebic meningoencephalitis--Myxomycete or Naegleria?

The 1968 New Zealand cases of primary amoebic meningoencephalitis are reviewed with reference to the identification of the aetiological organisms. Evidence is presented to show that they were Naegleria gruberi.


Dyspsychophobia: the abnormal fear of becoming psychologically and socially dysfunctional.

Six cases were mentioned in which the major factor was the pathological fear of developing various forms of mental illness or criminal behaviour that had assailed one or other of their relatives. The pathological fear had the characteristics of a particular phobia, and should be named as such as a preliminary towards psychotherapeutic treatment.


Psychiatric illness in general practice: a survey of opinions.

A general practitioners' attitude and opinion survey about psychiatric matters has been carried out on 69 Auckland general practitioners. The reported results are compared with the United Kingdom figures and some differences noted.


A computerised past medical history.

A patient questionnaire has been devised which is amenable to computer analysis, storage and retrieval. The computer prints out two copies of the condensed information, one for the patient and one for the doctor. The scheme has been tested in 100 patients in one practice and patient acceptability is 97 percent. The cost is between $2.50$2.50 and $10.00 per patient. The advantages of such a scheme to the patient, general practitioner, specialist and hospital are discussed.


The physician-specialist in Western Samoa.

An analysis of the work content of the physician-specialist at Apia General Hospital, Western Samoa, over a 12-month period in 1973-74 is described. Respiratory infections, rheumatic heart disease, hypertension, diabetes, peptic ulcer, and various forms of liver disease were encountered most commonly.


Unsealed radioactive materials in medical practice in New Zealand.

Information has been collected on numbers and types of radionuclide procedures in medical practice in New Zealand over a three-month period in the latter half of 1973. For in vivo procedures data on the age and sex of patients and the activities of radioactive materials administered were also collected. The changes in numbers of such procedures carried out over a seven-year period are discussed. A genetic radiation dose to the population of 0.24 mrad per person is derived for the year 1973, about 0.20 mrad of this dose arising from diagnostic procedures and 64 percent being attributable to brain imaging. Whereas formerly genetic doses have been estimated from data on activities of 131I and 32P used, this is no longer possible.


Separation of "sucrases" in supernatants of human dental plaque material and characterisation of the reaction products.

Dental plaque material, collected from five subjects, was pooled, homogenised and sonicated. The cell-free extracts and the remaining plaque suspension were incubated with sucrose. Approximately 14 per cent of the total "sucrase" activity was found in the cell-free extracts after homogenisation, 46 per cent in the cell-free extracts after sonication and 40 per cent in the remaining plaque suspension containing cell-fractions, respectively. Using gel chromatography of pooled plaque extracs from 10 subjects, active fractions were incubated with sucrose. The reaction products were isolated and characterised. The results indicate the presence of at least three groups of sucrose-splitting enzymes: dextransucrase, levansucrase and invertase.


An abbreviated index for periodontal bone height.

An abbreviated roentgenographic index for proximal periodontal bone height was developed which may be used to facilitate epidemiolgic research. Roentgenograms from about 2900 individuals aged 20 to 65 years and participating in epidemiologic surveys were used. The means of mesial plus distal bone levels from the mandibular molar plus premolar areas were found to satisfactorily represent the averages for the total dentition.


The influence of the cement layer on the strength of porcelain crowns subjected to frequent loading.

The aim of this investigation was to find out whether the support of cemented porcelain crowns was altered by repeated loading. The experiments were carried out  on porcelain caps cemented with zincphosphate cement to cores of dentine. One cap was made half the scale of the other. The proximal tensile stresses were determined from strains measured from attached strain gauges with a measuring bridge. The top of the caps were loaded at an angle of 60 degrees. The first measurement was made one hour after the cementation. A loading cycle of 6000 loadings was afterwards started. A second measurement was then made. The proximal tensile stresses were increased after the loading cycle. Only in the small model this increase was significant. This was probably because the cement layer was relatively thinner in the large model. The experiments suggested that repeated loading of porcelain crowns alter the support and then to increase the risk of fractures of the crowns. If the cement layer is thin, this risk is smaller.


Cardiovascular responses to intraosseous injections containing catecholamines.

The cardiovascular responses to Adrenaline and Noradrenalin, given intraosseously, are reported. Intraosseous injections of anesthetic containing catecholamines clearly demonstrate the rapidity with which the catecholamines are absorbed into the general circulation. Adrenalin-containing local anesthetic gave rise to rapid increases in the heart rate and blood pressure within a few seconds of the injection. Such cardiovascular responses, in many instances, were unacceptable to the subject because of the tachycardia and a feeling of intense tightness across the thorax. With Noradrenalin, on the other hand, the cardiovascular responses were asymptomatic, although it was usual for the heart rate to fall while the peripheral resistance and the blood pressure increased. Direct comparison was made, in the same persons, of infiltration and intraosseous injection of a Noradrenalin-containing local anesthetic. Insignificant responses were found with infiltration injections of catecholamines (0.9 ml. of 1/80,000 solutions) which is in agreement with previously published data. However, similar solutions injected intraosseously elicited cardiovascular responses. Although intraosseous injection of lidocaine hydrochloride containing 1/80,000 Noradrenalin appears clinically acceptable, a further search for anesthetics without effects on the cardiovascular system is desirable.


Temporomandibular ankylosis secondary to rheumatoid arthritis. Report of a case.

A case of unilateral bony ankylosis of the temporomandibular joint secondary to rheumatoid arthritis is presented, and the surgical treatment and postoperative regime are suggested. It is believed that, with proper motivation of the patient, an adequate oral opening may be maintained.


Postanesthetic necrotic defect.

An unusual defect was noted in a 10-year-old girl near the usual site of administration for an inferior nerve block. It was interpreted to be the result of a local anesthetic having been administered 2 months previously.


The use of intraoral dexamethasone after extraction of mandibular third molars.

All oral surgeions have encountered problems associated with edema, trismus, and pain after intraoral procedures. In third-molar surgery, pain and trismus are often directly proportional to edema. Therefore, in the patient with minimal edema, pain and trismus should be proportionally reduced. Parenteral use of the corticosteroid dexamethasone, given as a transoral injection at the time of operation, appears to be effective in the prevention of postoperative edema.


Orofaciodigital syndrome, type I: a phenotypic and genetic analysis.

An additional family with the orofaciodigital syndrome. Type I, is presented. On the basis of previously published pedigrees, as well as the present case, data are presented that conclusively support an X-linked dominant mode of inheritance. Segregation analysis demonstrated that not only is there lethality in the male but there is significant lethality in the female due to lyonization. In addition, a review of the familial cases will demonstrate a large degree of intra- and interfamilial variation.


Acute (toxic) epidermal necrolysis. Report of a case.

A case of acute (toxic) epidermal necrolysis is reported in the dental literature for the first time. This severe, life-threatening mucocutaneous syndrome resembles severely scalded skin. Sloughing vesiculobullous oral lesions are a frequent component. Staphylococcus aureus and drug reactions may cause separate entities presenting clinically as acute epidermal necrolysis. This case of drug-induced epidermal necrolysis ina child was successfully treated with methicillin and hydrocortisone.


Squamous odontogenic tumor. Report of six cases of a previously undescribed lesion.

Six cases of a previously unnamed oral lesion are described and the name squamous odontogenic tumor is applied. The lesion causes radiolucent areas of bone destruction adjacent to the roots of teeth. In one case there were multiple separate lesions. Light microscopy revealed numerous islands of benign squamous epithelium with focal areas of keratinization and calcification. Electron microscope examination in one case showed normal squamous epithelial cells with abundant glycogen granules, tonofilaments and myelin bodies. Complete surgical excision seems the best therapy, as only one lesion recurred following treatment.


Central mucoepidermoid tumors of the jaws. Report of nine cases and review of the literature.

Nine previously unreported cases of central mucoepidermoid tumor of the jaws (CMET) are presented and forty-one previously reported examples are reviewed. The mandible was involved in thirth-four cases and the maxilla in sixteen. The CMET is more common in females and has been reported in patients from 1 to 85 years of age. Most cases occur in the fourth and fifth decades. Radiographically, the CMET usually resembles an ameloblastoma or odontogenic cyst. Most CMET's are histologically well-differentiated lesions. Thirteen tumors recurred after various forms of therapy. Regional node metastasis was reported in four cases, and four patients died as a result of their tumors.


Anginal pain referred to the teeth. Report of a case.

A case is reported in which initial anginal pain was localized to the area of the left posterior teeth. Subsequently the patient reported that at certain times he experienced pain in the area of the left posterior teeth with concomitant chest pain while at other times the pain was confined to the teeth.


Adenomatoid odontogenic tumor (adenoameloblastoma). Report of a case.

A case of adenomatoid odontogenic tumor in which trauma was apparently a significant causative factor is presented. Consultation with an oral pathologist prevented unnecessary radical surgery.


Sialolithiasis: the radiolucent ones.

Radiolucent calculi are discussed. Three cases are presented, with a sialographic interpretation of each. Recent studies show that radiolucent calculi in general and parotid gland sialolithiasis in particular occur more frequently than was previously believed.


Clinical evaluation of 67Ga-citrate scanning in the oral region.

Gallium-67-citrate was administered to thirty-nine patients who had a variety of benign, malignant, and inflammatory lesions of the oral region. The gallium-67 scintigram was noted to be valuable in the diagnosis of maxillary carcinoma, parotid carcinoma, and malignant lymphoma. Clinically, it is possible to differentiate malignant tumors from benign ones with the aid of 67Ga scanning. It is difficult, however, to differentiate malignant tumors from inflammatory lesions. At present, it is difficult to defect the small malignant lesion by means of a 67Ga scintigram.


Chronic erythremic myelosis profiling a refractory anemia.

Chronic erythremic myelosis is a myeloproliferative disorder of unknown etiology that is characterized by refractory macrocytic anemia and marked megaloblastoid erythroid hyperplasia of the bone marrow. Ferrokinetic and cytologic evidence indicates that the disorder demonstrates ineffective erythropoiesis. Certain cytochemical tests may help both to substantiate the diagnosis and to provide insight into some of the biochemical abnormalities in the erythroid precursors. Therapeutic trials of androgen or pyridoxine (vitamin B6) or both may be of value in some cases but ineffective in others, and some patients may require administration of blood transfusions. Why an erythroid disorder characterized by a uniquetype of megaloblastoid erythropoiesis should be the forerunner of acute leukemia is one of the many unanswered questions in this often therapeutically frustrating disorder.


Effects of tetraalkylammonium salts on Brdicka and presodium currénts of bovine-serum albumin.

Tetraethyl-, tetrapropyl-, and tetrabutylammonium ions are capillary-active on the interface water-mercury. In the adsorbed state they increase Brdicka and presodium currents. These currents drop sharply at potentials where tetrabutylammonium ions are desorbed, these potentials being -1.60, -1.66, -1.72, and -1.79 V versus the saturated calomel electrode (SCE) at tetrabutyla-mmonium concentrations of 0.1, 0.25, 1, and 5 mM, respectively. Indications are that tetraethylammonium ions at a concentration of 50 mM are desorbed at a potential of the order of -1.9 V (versus SCE). The increase of Brdicka currents is attributed--at least in part--to a decrease in the rate of electroreduction of cobalt(II). In the desorbed state the effect--if any--of tetrabutylammonium ions on Brdicka and presodium currents is very small. Tetrabutylammonium ions also greatly increase Brdicka currents observed with cysteine, the effect disappearing after these ions attain their desorption potential. The effect of tetraphenylarsonium on Brdicka currents is very similar to that of tetrabutylammonium, while that of diphenylguanidine is similar to that of tetraethylammonium ions.


Synthetic analogs of active sites of iron-sulfur proteins: bis (o-xylyldithiolato) ferrate (III) monoanion, a structurally unconstrained model for the rubredoxin Fe-S4 unit.

To complete the set of synthetic analogs of the three recognized types of active sites in iron-sulfur redox proteins, the compound (Et4N)[Fe((SCH2)2C6H4)2], derived from o-xylyl-alpha,alpha'-dithiol, has been prepared and its structure has been determined by x-ray diffraction. The bischelate anion contains a near-tetrahedral Fe(III)-S4 coordination unit with small rhombic distortions and all Fe-S bond distances in the range 2.252-2.279 A. Its electronic properties have been partially characterized by measurement of electronic absorption, paramagnetic resonance, Mössbauer spectra, and magnetic susceptibility. The analog, as the protein, exhibits the Fe(III)/Fe(II) redox couple. These results substantiate designation of [Fe((SCH2)2C6H4)2]- as a synthetic analog of the Fe(III)(S-Cys)4 center in oxidized rubredoxin proteins. Comparison of the analog structure with that of the Clostridium pasteurianum rubredoxin active site shows that the former is substantially less distorted from idealized tetrahedral symmetry, and is considered to represent an essentially unconstrained structural model of the latter. Provided the grossly distorted tetrahedral stereochemistry of the protein site persists through final structural refinement, the analog-protein structural comparison supports an entatic state description of oxidized rubredoxin.


Donor properties of the three carbonyl groups of chlorophyll a: ab initio calculations and 13C magnetic resonance studies.

The relative donor properties of the three carbonyl groups of chlorophyll a have been studied theoretically by a series of ab initio molecular fragment, floating spherical Gaussian orbital, self-consistent field calculations on ethyl chlorophyllide a and experimentally through a 13C magnetic resonance study on chlorophyll a. The approximate ground state electronic wavefunction of ethyl chlorophyllide a was perturbed by monopole and dipole point charges whose signs, magnitudes, and positions were chosen to mimic the coulombic interactions associated with carbonyl coordination to Mg. Because the polarizability of the ring V keto carbonyl binding site is substantially greater than that for the ester carbonyl binding sites, the ring V keto binding site binds with smallest binding energy for weak perturbations and with largest binding energy for strong perturbations. A comparison of 13C magnetic resonance chemical shifts in chlorophyll a monomer and dimer provides new experimental evidence that the donor-acceptor interactions that bind the chlorophyll dimer together involve a substantial participation by the ring V keto carbonyl and minimal participation by the two ester carbonyl groups, and thus are in agreement with conclusions derived from the ab initio calculations.


Aspartic acid racemization in tooth enamel from living humans.

The aspartic acid in human tooth enamel shows increasing racemization with age. This increase is not seen in the metabolically active protein hemoglobin. The rate constant for the racemization reaction of aspartic acid in human tooth enamel was found to be 8.29 X 10(-4) yr-1. This rate constant suggests that in any protein with a long in vivo lifetime, D-aspartic acid will accumulate with age (about 8% of total aspartic acid in enamel will be the D-enantiomer after 60 years). Thus, racemization may play some role in the aging process affecting metabolically stable tissues in long-lived homeotherms. Aspartic acid racemization in toogh enamel also provides a biochronological tool for assessing the age of living mammals.


Synthesis of RNA containing a methylated blocked 5' terminus by HeLa nuclear homogenates.

RNA synthesized in vitro by HeLa nuclei contains a variety of blocked methylated 5'-terminal structures that can be grouped into four general types: (a) m(7)GppN(m)p...; (b) m(7)GppN(m)pM(m)p...; (c) m(7)GpppN(m)p...; and (d) m(7)GpppN(m)pM(m).... Both N(m) and M(m) can be either one of the four 2'-O-methylated nucleosides. The relative amounts of the N(m) species are G = 45%, A = 25%, U = 20%, and C = 10%.


Increased frequency of initiation of RNA synthesis due to a protein factor from chicken myeloblastosis nuclei.

The mechanism of the effect of an RNA polymerase II (RNA nucleotidyltransferase II) stimulation factor isolated from the nuclei of chicken myeloblastosis cells was studied. The stimulation requires the presence of all four nucleoside triphosphates and depends upon an exogenous DNA template. In the absence of the factor, RNA synthesis ceases after 20-30 min, but in the presence of the factor, synthesis continues up to 60-80 min. Addition of the factor at 35 min after incubation causes resumption of RNA synthesis. The factor greatly stimulates the activity of RNA polymerase II at low enzyme concentrations. The RNA polymerase activity is more sensitive to alpha-amanitin inhibition when the factor is present. Experiments of [gamma-32P]ATP incorporation reveal that the factor provides for an increased frequency of initiation of RNA chains, both of the primary initiation events and re-initiation after previous ones were completed. A slightly higher rate of RNA chain growth was also observed with this factor but the ultimate size of RNA synthesized was not affected, as determined by formaldehyde/sucrose gradient centrifugation. These data suggest that the factor functions at the initiation stages of the RNA polymerase reaction.


Interaction of elongation factor Tu with 2'(3')-O-aminoacyloligonucleotides derived from the 3' terminus of aminoacyl-tRNA.

The interaction between Escherichia coli elongation factor-Tu-GTP complex and chemically synthesized 2'(3')-O-aminoacyldinucleoside phosphates with the nucleotide sequence of the 3' terminus of aminoacyl-tRNA (AA-tRNA) has been studied. It was found that C-A-Phe, C-A-Pro, and C-A-Asp interact with EF-Tu-GTP, causing the release of GTP bound to the enzyme. The specificity of this interaction closely resembles that of AA-tRNA since C-A and C-A(Ac-Phe) as well as the corresponding tRNAs are inactive. The 3'-O-aminoacyl derivative C-2'-dA-Phe does not interact with EF-Tu-GTP, whereas the 2'-O-aminoacyl derivative C-3'-dA-Phe is almost as active as the 2'(3')-O-aminoacyl derivative, C-A-Phe. C-A-Phe also interacts with the EF-Tu-GDP complex in a manner similar to its interaction with EF-Tu-GTP. It is concluded that interaction of 2'(3')-O-aminoacyloligonucleotides possessing the sequence of the 3' terminus of AA-tRNA is analogous to the interaction of that terminus with EF-Tu and it is suggested that EF-Tu is specific for 2'-O-AA-tRNA.


Electrophoretic patterns of deadenylylated chorion and globin mRNAs.

Treatment of silkmoth chorion mRNAs with calf thymus RNase H (EC 3.1.4.34; RNA-DNA-hybrid ribonucleotidohydrolase) in the presence of oligo(dT) specifically and effectively removes the 3'-terminal poly(A) sequences. Excision of non-poly(A) fragments cannot be detected. Under these conditions, RNase H leads to increased electrophoretic homogeneity of rabbit globin mRNA, presumably as a result of removal of poly(A) sequences that are inherently variable in length. Treatment with RNase H converts the three diffuse zones of messages for the several chorion proteins into multiple sharp bands.


Amino-acid sequence and oligosaccharide attachment sites of human erythrocyte glycophorin.

Glycophorin, the major sialoglycoprotein of the human erythrocyte membrane, is composed of 131 amino acids and an average of 16 oligosaccharide chains. Fifteen oligosaccharides are linked to threonine/serine residues via O-glycosidic bonds, and one more complex unit is attached to asparagine. The location of each of these oligosaccharides and the complete amino-acid sequence of this molecular have been determined by Edman degradation techniques. Glycophorin appears to be organized into three distinct "domains" on the basis of the locations of glycosylated amino acids and the clustering of residues of similar type. These include (i) a glycosylated segment composed of approximately 64 residues from the NH2-terminus, (ii) a "hydrophobic" segment of approximately 32 nonpolar residues, and (iii) a COOH-terminal segment, composed of approximately 35 residues, which has an unusual concentration of hydrophilic amino acids. This unique structure is consistent with the earlier suggestions that glycophorin is one of the major "intrinsic" membrane proteins which has a transmembrane orientation.


Thromboxanes: a new group of biologically active compounds derived from prostaglandin endoperoxides.

An unstable [t1/2 at 37 degrees = 32 +/- 2 (SD) sec] intermediate, thromboxane A2, was detected in the conversion of prostaglandin G2 into 8-(1-hydroxy-3-oxopropyl)-9,12L-dihydroxy-5,10-heptadecadienoic acid (thromboxane B2) in platelets. The intermediate was trapped by addition of methanol, ethanol, or sodium azide to suspensions of washed human platelets incubated for 30 sec with arachidonic acid or prostaglandin G2. The structures of the resulting derivatives demonstrated that the intermediate possessed an oxane ring as in thromboxane B2 but lacked its hemiacetal hydroxyl group. Additional experiments using 18O2 or [2H8]arachidonic acid in the formation of thromboxane B2 and CH3O2H for the trapping of thromboxane A2, together with information on the t1/2 of the intermediate, indicated the presence of an oxetane structure in thromboxane A2. Incubation of arachidonic acid or prostaglandin G2 with washed platelets led to formation of an unstable factor that induced irreversible platelet aggregation and caused release of [14C]serotonin from platelets that had been incubated with [14C]serotonin. The properties and the mode of formation of this factor indicated that it was identical with thromboxane A2. Furthermore, evidence is presented that the more unstable and major component of rabbit aorta contracting substance (RCS) formed in platelets and guinea pig lung is also thromboxane A2.


Activation volumes in enzymic catalysis: their sources and modification by low-molecular-weight solutes.

Changes in enzyme conformation are often accompanied by large changes in volume. Model compound studies suggest that these volume changes may derive from two sources: (i) "hydration density" effects due to changes in the exposure to solvent of protein groups which modify water density, and (ii) "structural" contributions arising from changes in the volume of the protein itself. An experimental approach was developed to test the validity of the predictions based on model compound studies for catalytic conformational changes. By examining the effects of different solutes on the activation volumes of different enzymic reactions, we show that both sources of volume change provide significant contributions to the activation volume.


A rapid and specific method for isolation of thiol-containing peptides from large proteins by thiol-disulfide exchange on a solid support.

Activated thiol-Sepharose [agarose-(glutathione-2-pyridyl disulfide) conjugate] has been used to immobilize proteins with a single or a few thiol groups via disulfide bridges. The immobilized proteins were subsequently proteolytically degraded. After washing, the thiol-containing peptides were eluted with a reducing agent. A single preparative paper electrophoresis, occasionally after a modification such as oxidation, was sufficient to obtain pure peptides in good yields. The method was applied to the major parvalbumin from hake muscle (a protein with 108 amino acid residues and one cysteine residue), to mercaptalbumin from bovine serum (565 residues and one cysteine), and to human serum ferroxidase [EC 1.16.3.1; iron (II):oxygen oxidoreductase] (ceruloplasmin) (1065 residues and three cysteines). The use of the technique, e.g., as a simple means of obtaining homologous peptides in related proteins, is discussed.


On primary structure and biosynthesis of histidine-rich polypeptide from malarial parasite Plasmodium lophurae.

Experiments on the primary structure of a histidine-rich polypeptide isolated from the malarial parasite Plasmodium lophurae indicate that the smaller quantities of amino acids other than histidine form an integral part of the polypeptide and do not arise from a protein contaminating a histidine homopolymer. In culture, the parasites incorporate over 50% of exogenously supplied histidine into the histidine-rich polypeptide and this incorporation is inhibited by puromycin.


Absence of polyadenylate segment in globin messenger RNA accelerates its degradation in Xenopus oocytes.

Rabbit globin poly(A)-free and native mRNA preparations were microinjected into Xenopus oocytes. The amount of globin message remaining after incubation of injected oocytes was determined by molecular hybridization with a radioactive complementary DNA probe, synthesized by copying globin mRNA with purified RNA-dependent DNA polymerase (reverse transcriptase) from avian myeloblastosis virus. The results show that 56 hr after injection about 85% of the poly(A)-free mRNA molecules are degraded, while native poly(A)-containing mRNA chains are almost completely preserved during the same period of time.


Bovine factor X1 (Stuart factor): amino-acid sequence of heavey chain.

The amino-acid sequence of the heavy chain of bovine blood coagulation factor X1 (Stuart factor) isolated before and after activation has been determined. Sequence analysis was performed on fragments obtained by cleavage with cyanogen bromide and by tryptic digestion. Comparison of the complete sequence with those of other hepatic and pancreatic serine proteases demonstrates homology of the heavy chain of activated factor X1 (factor X1a) with the B chain of bovine thrombin as well as with bovine trypsin, chymotrypsins A and B, and porcine elastase. The activation peptide cleaved near the amino terminus by a protease from Russell's viper venom differs in both size and sequence from those of other serine proteases. With three exceptions, all of the residues which are important in the catalytic functions of trypsin and chymotrypsin occur in corresponding loci in the heavy chain of factor Xa. These finding suggest that the three-dimensional structure of the heavy chain is similar to that of the pancreatic serine proteases and that these enzymes have evolved from a common ancestral gene.


Dual regulation of adenylate cyclase accounts for narcotic dependence and tolerance.

Narcotics affect adenylate cyclase [ATP pyrophosphate-lyase (cyclizing), EC 4.6.1.1] in two opposing ways, both mediated by the opiate receptor. The first process is the readily reversible inhibition of the enzyme by narcotics; the second is a compensatory increase in enzyme activity which is delayed in onset and relatively stable. Late positive regulation of the enzyme counteracts the inhibitory influence of morphine and is responsible for narcotic dependence and tolerance. The coupled inhibitory and positive regulatory mechanisms for adenylate cyclase provide a means of activating and deactivating neural circuits hours after the initial event and thus may play a role in a memory process.


Molecular mechanism for oscillation in flagella and muscle.

Two-state models for muscle cross-bridges, of the type originally detailed by Andrew Huxley, were examined. Rate functions for cross-bridge attachment and detachment can be chosen which yield a steady-state force-velocity relationship appropriate for the spontaneous generation of oscillatory contractions. Computer simulations have been used to demonstrate oscillation of such cross-bridge systems, and to demonstrate that distribution of this type of local shear oscillation along the length of a flagellum is sufficient for the generation of propagated bending waves.


Brownian motion in biological membranes.

Brownian motion (diffusion) of particles in membranes occurs in a highly anisotropic environment. For such particles a translational mobility (independent of velocity) can be defined if the viscosity of the liquid embedding the membrane is taken into account. The results of a model calculation are presented. They suggest that for a realistic situation translational diffusion should be about four times faster in relation to rotational diffusion than in the isotropic case.


Gene expression in mouse neuroblastoma cells: properties of the genome.

Chromatin was prepared from isolated nuclei of proliferating and differentiated cultures of C1300 mouse neuroblastoma cells. Differentiation was induced by serum withdrawal or treatment with dibutyryl cyclic AMP. The ability to support DNA-dependent RNA synthesis when assayed in a cell-free system is three times greater for chromatin from proliferating cells. Histones isolated from proliferating and differentiated cells were fractionated electrophoretically. The relative amounts of proteins present in the five major histone fractions were similar. In contrast, there were significant differences in the nonhistone chromosomal proteins synthesized and associated with the genome of proliferating and differentiating neuroblastoma cells. Such differences are reflected by modifications in the electrophoretic banding patterns and in incorporation of [3H]tryptophan into various molecular weight classes of nonhistone chromosomal polypeptides. A functional relationship between changes in the nonhistone chromosomal proteins and variations in the transcriptional activity accompanying differentiation of neuroblastoma cells may exist.


Chromosomal localization of human genes governing the interferon-induced antiviral state.

Interferon sensitivity of different normal and aneusomic human cells and of different mouse-human hybrids cells has been compared. G21 trisomic cells are more sensitive than diploid cells; whereas, on the contrary, triploid cells are normal in their human interferon sensitivity. Among other aneusomic cell lines tested, E16 trisomic cells are significantly less sensitive. These data are in favor of the hypotheses that the G21 chromosome carries genetic information for structural proteins involved in the receptor system for interferon, that there is a regulatory mechanism governing the antiviral state, and that the E16 chromosome is a possible candidate for carrying information for such a depressive regulatory mechanism. None of the chromosome abnormalities studies are involved with interferon synthesis.


Chromatin and DNA synthesis associated with nuclear membrane in germinating cotton.

The synthesis of nuclear DNA and possible attachment sites of chromatin in the cells of cotton (Gossypium barbadense) radicles during germination was investigated. Biochemical analysis of nuclear membrane fragments or Sarkosyl-magnesium-membrane complexes indicates that the DNA, including newly replicated DNA, is attached to the nuclear membranes during periods of active synthesis. Electron micrographs of nuclear membrane fragments indicate a physical association between chromatin fibers and the membranes. The attachment site appears to be proteinaceous, since the chromatin is released by protein degradative enzymes as evidenced by biochemical techniques and electron microscopic observations. Short-term labeling results in incorporation into a membrane-associated product indistinguishable from the bulk of nuclear DNA. DNA polymerase activity is also associated with nuclear membrane preparations in which [3H]thymidine triphosphate is incorporated into an acid-insoluble. DNase-sensitive product.


Growth-dependent alterations in oligomannosyl cores of glycopeptides.

Mannose-labeled glycopeptides from the surface of growing and nongrowing human diploid cells (KL-2) were separated into neutral glycopeptides and acidic glycopeptides by paper electrophoresis. Growth-dependent alterations occurred in oligomannosyl cores in the neutral glycopeptides; namely, the neutral glycopeptides from the surface of growing cells were more resistant to endo-beta-N-acetylglucosaminidase D but were more susceptible to alpha-mannosidase (EC 3.2.1.24; alpha-D-mannose mannohydrolase) than those derived from the surface of nongrowing cells. Another growth-dependent change was found when the endoglycosidase-resistant material from acidic glycopeptides was compared by paper electrophoresis at pH 1.9. The material from the surface of nongrowing cells contained a component that was absent or greatly reduced in growing cells.


On the alleged high sensitivity of mouse Ehrlich-Lettre ascites tumor cells to diphtheria toxin.

It was recently reported by Iglewski and Rittenberg in THESE PROCEEDINGS (71, 2707-2710, 1974) that low doses of purified diphtheria toxin inhibit protein synthesis in mouse Ehrlich-Lettre ascites carcinoma cells cultured in vitro. These observations could not be confirmed by us nor could the authors' further claim that toxin can cause regression of well-established ascites tumors in preimmunized mice be confirmed. Although temporary regression of such tumors can be demonstrated in unimmunized mice following intraperitoneal injection of diphtheria toxin, the amounts of toxin required are high and approach the lethal dose. About the same amount of CRM45, a tox gene product serologically related to diphtheria toxin but only 1/10,000th as toxic for guinea pigs, will also cause temporary regression in tumor-bearing mice.


The major cell surface glycoprotein of chick embryo fibroblasts is an agglutinin.

A major cell surface protein, CSP, of chick embryo fibroblasts has been shown to constitute up to 3% of total cell protein, and to be decreased after viral transformation. Its role in normal cell behavior is not known. We have isolated CSP from chick embryo fibroblasts by extraction with 1 M urea and find that these preparations of CSP agglutinate formalinized sheep erythrocytes at protein concentrations of under 2 mug/ml. In extracts of chick embryo cells, the quantity of such hemagglutinating activity parallels that of CSP determined by electrophoresis, and both are substantially decreased in chick cells transformed by the Bryan hightiter strain of Rous sarcoma virus. Both CSP and hemagglutinating activity are progressively adsorbed onto erythrocytes and can be released by 1 M urea. An antiserum to purified CSP specifically blocks the agglutination. The agglutinating activity is destroyed by boiling or treatment with proteases. The agglutination reaction is inhibited by the chelating agents EDTA and EGTA [ethyleneglycol-bis(beta-aminoethyl ether)N,N'-tetraacetic acid]. Agglutination is also inhibited to a lesser degres by amino sugars and other amines, increased osmolarity, and urea. Other monosaccharides, hyaluronidase, DNase, and RNase have little or not effect on the agglutination reaction. This demonstration that CSP has an agglutinating activity that is sensitive to proteases and that requires divalent cations suggests that this molecule may play a role in cell adhesion.


Synthesis of vitellogenin in cultures of male and female frog liver regulated by estradiol treatment in vitro.

Using the frog Xenopus laevis, we show that the addition of physiological concentrations of estradiol to cultures of liver from untreated males rapidly induces the synthesis of large amounts of vitellogenin. Sustained synthesis of vitellogenin requires continuous exposure to estradiol. A nonestrogenic steroid, dexamethasone, does not induce vitellogenin synthesis but does induce increased synthesis of a different protein in liver cultures.


Genetic complementation in heterokaryons of human fibroblasts defective in cobalamin metabolism.

Inherited methylmalonicacidemia due to deficiency of methylmalonyl-CoA mutase (methylmalonyl-CoA CoA-carbonylmutase; EC 5.4.99.2) activity results from at least three classes of biochemically distinct defects affecting cobalamin (Cbl: vitamin B12) metabolism (cbl A, cbl B, and cbl C mutants) and a fourth class producing a defective mutase apoenzyme. We have obtained genetic evidence in support of this biochemical heterogeneity, using heterokaryons prepared by Sendai-virus-mediated cell fusion. Nine fibroblast lines from patients with defective Cbl metabolism (4 cbl A, 3 cbl B, and 2 cbl C), two from patients with defective mutase apoenzyme, and two from controls were fused in pairwise combinations and tested for functional mutase holoenzyme using a radioautographic procedure which detects [14C]propionate incorporation into trichloroacetic-acid-precipitable material in fibroblast monolayers in situ. Each of the mutants incorporates negligible radioactivity compared to control cells. Activity is also negligible when different mutants are mixed without virus or when homokaryons are produced by self-fusion. Heterokaryons produced by fusing members of each of the four mutant classes with representatives of any other class recover the ability to incorporate [14C]propionate to levels comparable to those of control cells. However, heterokaryons produced between members of the same class fail to complement in all cases. We conclude that the mutants with defective Cbl metabolism (cbl A, cbl B, cbl C) comprise three complementation groups, that a fourth group corresponds to mutase apoenzyme deficiency, and that all four classes of mutations are recessively inherited.


Mutagenicity of chloroacetaldehyde, a possible metabolic product of 1,2-dichloroethane (ethylene dichloride), chloroethanol (ethylene chlorohydrin), vinyl chloride, and cyclophosphamide.

We have previously described a very sensitive and efficient bacterial test designed to detect chemical carcinogens as mutagens. Chloroacetaldehyde is mutagenic in this system and is of interest because it is a possible metabolite in mammals of the large volume industrial chemicals 1,2-dichloroethane (ethylene dichloride) (3.5 billion kg/yr, U.S.) and vinyl chloride (2.5 billion kg/yr, U.S.), and of the antineoplastic agent cyclophosphamide. Chloroacetaldehyde reverts a new Salmonella bacterial tester strain (TA100). Chloroacetaldehyde is shown to be hundreds of times more effective in reversion of TA100 than is chloroethanol (ethylene chlorohydrin), a known metabolic precursor of chloroacetaldehyde and a possible metabolite of dichloroethane and vinyl chloride, or than vinyl chloride, which is itself mutagenic for TA100. Chloroethanol is shown to be activated by rat (or human) liver homogenates to a more highly mutagenic form with reversion properties similar to chloroacetaldehyde. Reversion properties of cyclophosphamide after in vitro metabolic activation suggest that chloroacetaldehyde is not the active mutagenic form of this antineoplastic drug.


Statistical analyses of Drosophila and human protein polymorphisms.

By using the distribution function of allelic frequencies which was recently derived by Kimura and Ota for the model of stepwise production of neutral alleles, the observed protein polymorphisms of Drosophila and man are tested for fit to the theory of neutral protein variation. The observed and theoretical distributions of alleles agree quite well except for the excess of rare alleles in the actual distributions. In human polymorphisms, the alleles with frequencies less than 1% are more numerous than expected, whereas in Drosophila, those with frequencies less than 10% are more numerous. It is pointed out that these results support my thesis that mutational pressure rather than balancing selection is the main cause for the maintenance of protein polymorphisms.


Structural similarities between a product of the T/t-locus isolated from sperm and teratoma cells, and H-2 antigens isolated from splenocytes.

Molecules specified by the H-2-linked T/t locus in the mouse are expressed on H-2-negative cells such as early embryos, sperm, and teratoma cells. By means of enzymatic radioiodination of cells and immunoprecipitation of lysates with congenic antiserum, one of these molecules, known as F9, has been obtained from sperm and teratoma cells and compared to H-2 isolated from murine splenocytes. Our studies indicate that both H-2 and F9 have identical molecular weights and subunit structure, including the presence of a B2-microglobulin-like subunit. These findings, taken together with previous studies of TL alloantigens, suggest that a number of gene products of the 9th linkage group show structural homology with each other and, in addition, with immunoglobulin. The genes in question may therefore have arisen from a primitive gene concerned with cellular recognition.


Properdin: initiation of alternative complement pathway.

Activation of the classical complement (C) system involves conversion of C1 to its active state with subsequent cleavage of C4 and  -d C2 so as to form the classical C3 convertase, C42 (a bar indicates the activated form of a protein), which sequentially cleaves C3 and C5 to initiate the cytolytic event associated with the complete reaction. An alternative, pr properdin-dependent, pathway to complement activation generates a C3 convertase, C3B, that is formed by cleavage of B with D in the presence of a C3b, the major cleavage fragment of C3. C3b is capable of binding activated properidin (P) with resultant stabilization of C3B, which otherwise rapidly decays by loss of B activity. Initial cleavage of C3, a prerequisite for formation of C3B, is demonstrated to occur through the interaction of native C3 and B in the presence of either D or P alone, or together. The effect of P on the interaction of D, B, and C3 is attributed to stabilization of C3B as has been shown for C3B. Larger amounts of P and B with C3 in the absence of D form a C3 convertase that is designated (P)C3B to indicate that demonstrable cleavage of B does not occur although the active site is available. The generation of this initial convertase, as assessed by C3 inactivation, is dose-related to P and B inputs. The presence of both P and D greatly augments initial cleavage of C3 with D fully uncovering the active site of B and P stabilizing that site.


Aggression patterns and speciation.

The evolutionary significance of interspecific aggression as a factor in speciation was tested among three chromosome forms of the actively speciating fossorial rodent Spalax ehrenbergi in Israel. Laboratory experiments testing intra- and interspecific aggression were conducted on 48 adult animals from 10 populations comprising three chromosome forms with 2n = 52, 58, and 60. Twelve agonistic, motivational-conflict, and territorial behavioral variables were recorded during 72 combats involving homo- and heter-ogametic encounters between opponents. Analysis of the data matrix was carried out by the nonmetric multivariate Smallest Space Analysis (SSA-II). The results indicate that (a) aggression patterns, involving agonistic conflict and territorial variables, are higher in heterogametic encounters than in homogametic ones; and (b) aggression is higher between contiguous chromosome forms (2n = 58-60, and 2n = 52-58) than between noncontiguous ones (2n = 52-60). Both a and b suggest that high interspecific aggression appears to be adaptively selected at final stages of speciation in mole rats as a premating isolating mechanism which reinforces species identification and establishes parapatric distributions between the evolving species.


The ovary as a source of alpha-ecdysone in an adult mosquito.

The ovaries of the mosquito Aedes aegypti cultured in vitro secrete material that behaves like ecdysone in a radioimmunoassay. The material was identified as alpha-ecdysone by high-resolution liquid and gas-liquid chromatography. Secretion reached a maximum 16 hr after a blood meal as shown by bioassay and direct determination. Ovariectomy reduced the concentration of ecdysone in the adult after a blood meal. Qualitative analysis of whole-body extracts indicated beta-ecdysone to be the principal species present. Thus the ovaries appear to secrete a prohormone, alpha-ecdysone, which is converted to beta-ecdysone. Beta-ecdysone plays a significant role in stimulating egg development in the adult mosquito and may have reproductive roles in other insects.


Ribonuclease-sensitive DNA-synthesizing complex in human sperm heads and seminal fluid.

An endogenous DNA-synthesizing complex sensitive to ribonuclease has been found in purified preparations of swollen human sperm heads. Incorporation of [3H]dTTP into acid-precipitable material occurred in the presence of actinomycin D and required addition of dGTP, dCTP, dATP, plus Mg++. Polymerization was sensitive to pretreatment of the complex with pancreatic RNase A or Triton X-100. Exogenous activity was elicited by the synthetic template (dT)12--18-(rA)n but not by (dT)12--18-(dA)n or (dT)10. The complex sedimented from a 10,000 X g supernatant by centrifugation at 165,000 X g for 60 min and banded in sucrose at a density of 1.21--1.25 g/cm3. Endogenous RNase-sensitive DNA polymerase activity from cell-free seminal fluid was also detected in a fraction in sucrose at a density of 1.22 g/cm3. This activity was labile to freezing and stimulated by 0.04% Triton X-100, and thus differed from that of sperm heads.


Transcription termination and late control in phage lambda.

A transcription termination site occurs between the promoter for late gene expression of bacteriophage lambda and the late genes themselves. It is proposed that the lambda Q gene product controls late gene expression by over-coming this termination barrier.


Protein hydration changes during catalysis: a new mechanism of enzymic rate-enhancement and ion activation/inhibition of catalysis.

There exists a linear correlation between the effect of a salt on the rate of an enzymic reaction and its effect on the activation volume (delta V++) of the reaction. Salts that increase delta V++ invariably decrease the rate of the reaction, and vice versa. The salt effects on reaction rate are, however, much larger than would be predicted solely on the basis of pressure-volume work changes deriving from the observed alterations in delta V++. Different inorganic salts affect reaction rates and activation volumes in a manner that reflects the salts' positions in the Hofmeister series. These observations, taken in conjunction with data on the effects of salts on protein functional group (aminoacid side-chains and peptide linkages) hydration, lead us to propose the following hypothesis to account for salt activation and inhibition of catalysis. Aminoacid side-chains and peptide linkages located on or near the protein surface change their exposure to water during conformational events in catalysis. These protein group transfers are accompanied by large volume and energy changes that are due largely to changes in the organization of water around these groups. When these transfer processes occur during the rate-limiting step in catalysis, these energy and volume changes can contribute to the free energy of activation (delta G++) and the activation volume of the reaction. By influencing the degree to which water can organize around transferred protein groups, salts can modify both the delta G++ (rate) and the delta V++ of a reaction.


Changes in ribosomal RNA processing paths in resting and phytohemagglutinin-stimulated guinea pig lymphocytes.

Processing of rRNA was examined in resting and phytohemagglutinin-stimulated guinea pig lymphocytes. Synthesis of 1.7 (28S) and 0.7 (18S) X 10(6) dalton rRNA was more than 4-fold greater in phytohemagglutinin-stimulated than in resting cells. A 5- to 10-fold increase in flux of molecules through a 2.3 X 10(6) dalton RNA occurred without a concurrent change in the flux through a 2.6 X 10(6) dalton fraction in phytohemagglutinin-stimulated cells. In both resting and phytohemagglutinin-stimulated lymphocytes, the 2.3 X 10(6) dalton intermediate equilibrated with [3H]methyl label and pulse-chased prior to the 2.6 X 10(6) dalton RNA. The data indicate at least two processing paths in guinea pig lymphocytes; one proceeds to rRNA via a 2.3 X 10(6) dalton intermediate, and another proceeds via a 2.6 X 10(6) dalton RNA. The increase in rRNA synthesis in phytohemagglutinin-stimulated cells occurs primarily through that path containing the 2.3 X 10(6) dalton intermediate.


Electron microscopy of defined lengths of chromatin.

Defined lengths of chromatin were prepared by brief digestion with micrococcal nuclease and fractionation in a sucrose gradient. A length containing a given number of 200 base pair repeating units appeared as the same number of 100 A beads in the electron microscope. The distance between beads within a length was small, usually less than about 20 A.


Chinese hamster ovary cells selected for resistance to the cytotoxicity of phytohemagglutinin are deficient in a UDP-N-acetylglucosamine--glycoprotein N-acetylglucosaminyltransferase activity.

Several clones of Chinese hamster ovary cells resistant to the cytotoxicity of the phytohemagglutinin from Phaseolus vulgaris show decreased binding of 125I-labeled phytohemagglutinin and contain decreased levels of a UDP-N-acetylglucosamine--glycoprotein N-acetylglucosaminyltransferase (EC 2.4.1.51; UDP-2-acetamido-2-deoxy-D-glucose:glycoprotein 2-acetamido-2-deoxy-D-glucosyltransferase) activity when compared to wild-type cells. The decrease in transferase activity varies from 45% to 96%, depending on the exogenous acceptor used in the enzyme assay. No differences between lectin-resistant and wild-type cells were noted for several other glycosyltransferases. The absence of a particular N-acetylglucosaminyltransferase in the lectin-resistant cells apparently results in defective glycosylation of lectin-binding glycoproteins on the cell surface. A phytohemagglutinin-resistant clone which shows decreased binding of 125I-labeled phytohemagglutinin but does not exhibit the enzyme deficiency has also been isolated.


Chemical and physical properties of fractionated chromatin.

Sonicated chicken reticulocyte chromatin was fractionated into transcriptionally active and transcriptionally repressed components. The active fraction is 8% of the whole chromatin but contains 70% of the newly synthesized chromosomal RNA. This RNA has five times as many hemoglobin RNA sequences as does the RNA in the repressed fraction. The amount of the active fraction in the chromatins of several tissues correlates with their synthetic activity. The molecular weight of the DNA of the repressed fraction is approximately twice that of the active fraction. Moreover, the configuration of repressed chromatin is much more compact, consistent with a much larger sedimentation constant. The transcriptionally active fraction displays a 6 degrees lower melting profile and is highly susceptible to DNase I relative to the repressed fraction. The active fraction contains twice as much non-histone protein and 15% less histone than the repressed fraction and is lacking the lysine-rich and much of the arginine-rich histones.


A model for compartmentation of de novo and salvage thymidine nucleotide pools in mammalian cells.

When [3H]thymidine is added to HeLa cells grown in thymidine-free medium it is incorporated into DNA almost immediately at full specific activity, blocking any further incorporation of de novo synthesized thymidine nucleotides. Apparently, de novo nucleotide pools [Baumunk, C.N. & Friedman, D.L. (1971) Cancer Res. 31, 1930--35] and salvage nucleotide pools are compartmentalized in HeLa cells. After one generation in the presence of thymidine, the cells begin utilizing nucleotides from both pools to about equal extent.


Correlation of moth sex pheromone activities with molecular characteristics involved in conformers of bombykol and its derivatives.

Molecular characteristics of bombykol and its 11 derivatives, which reveal significant correlations with biological activities for single sex pheromone receptor cells of four moth species, Bombyx mori, Aglia tau, Endromis versicolora, and Deilephila euphorbiae, were examined on the assumption of the "bifunctional unit model." Probabilities of bifunctional unit formations of those 12 compounds were assessed with frequency distribution patterns of distances between the proton acceptor, the proton donor, and the methyl group involved in a total of 1,200 conformers. A highly significant correlation exists between biological activity for each species and the probability of a particular bifunctional unit formation: a proton acceptor (A)--a methyl group (Me) unit (A--Me distances: about 6 A) for Deilephila (r = 0.94); a proton acceptor (A)--a proton donor (D)(A--D: about 11 A) for Aglia (r = 0.83); two antagonistic proton donor--methyl units (D--Me: about 14 and 5 A for favorable and adverse unit, respectively) for Bombyx (r = 0.94) and Endromis (r = 0.92).


Fluorescence polarization and viscosities of membrane lipids of 3T3 cells.

Studies of the fluorescence polarization of 1,6-diphenyl-1,3,5-hexatriene in membranes of normal, transformed, and revertant 3T3 cells allowed estimation of microviscosities (eta) of the lipid bilayers of these cells. Fluorescence polarization values observed with normal cells were significantly lower than those observed with cells transformed either by polyoma virus or by simian virus 40. The values of fluorescence polarization obtained with revertant Py6R1 cells were lower than those obtained with the normal cells. The calculated microviscosities (eta) show a 50% increase upon transformation. Possible correlations between the bilayer viscosity and the mobility of the receptors in the membrane are discussed.


Synthesis and biological properties of a 9,11-azo-prostanoid: highly active biochemical mimic of prostaglandin endoperoxides.

The 9,11-azo-prostanoid III [(5Z, 9alpha, 11alpha, 13E, 15S)-9, 11-azo-15-hydroxyprosta-5,13-dienoic acid] has been obtained by synthesis and tested for biological activity in systems which are responsive to the prostaglandin endoperoxides PGH2 (I) and PGG2 (II). The azo analog III is a powerful mimic of these endoperoxides with reference to platelet aggregation and release of serotonin when added to human platelet-rich plasma. The analog III is substantially more active (about 7 fold) than PGG2 in stimulating muscle contraction in the isolated rabbit aorta strip. The very great stability of III relative to PGH2 and PGG2 and its potency as a mimic of these important substances suggest that this azo analog will be of considerable value in future studies of the prostaglandin endoperoxides.


Activation of bovine factor X (Stuart factor): conversion of factor Xaalpha to factor Xabeta.

Bovine factor X (molecular weight 55,100) is a blood coagulation factor present in plasma in a precursor or zymogen form. It is a glycoprotein which has been isolated as a two-chain structure held together by one or more disulfide bonds. During the coagulation process, factor X is converted to a serine protease by the hydrolysis of a specific peptide bond in the amino-terminal region of the heavy chain. This cleavage occurs between Arg-51 and Ile-52, giving rise to factor Xaalpha (molecular weight 45,300) and an activation peptide (molecular weight 9500). Factor Xaalpha is then converted to factor Xabeta (molecular weight 42,600) by hydrolysis of a second specific peptide bond in the carboxyl-terminal region of the heavy chain. This cleavage occurs between Arg-290 and Gly-291, giving rise to a second glycopeptide (molecular weight 2700). Factor Xaalpha and factor Xabeta have equivalent coagulant activity, indicating that the cleavage of the second peptide bond is unrelated to the activation process.


Effect of estrogen on gene expression: purification of vitellogenin messenger RNA.

We report initial studies on estrogen-mediated regulation of egg yolk protein synthesis in the rooster. Egg yolk proteins are normally synthesized as a large precursor, vitellogenin, in the liver of the laying hen; roosters synthesize vitellogenin only when treated with estrogen. Polysomal RNA from the liver of estrogen-treated roosters was translated in a reticulocyte cell-free system, and the newly synthesized proteins were identified by a highly specific and sensitive indirect immunoprecipitation reaction. The messenger RNA that specifies vitellogenin has been purified more than 800-fold from rooster liver polysomal RNA by a combination of methods, including immunoprecipitation of polysomes and chromatography of RNA on poly(U)-Sepharose.


Bacterial luciferase requires one reduced flavin for light emission.

Recent reports revive a hypothesis that the bacterial bioluminescence reaction involves two reduced flavin mononucleotide molecules per enzyme turnover. A two-flavin mechanism requires that the two flavins bind simultaneously or sequentially to the same or different sites on luciferase during a catalytic cycle. Measurements using equilibrium techniques show that the luciferase dimer has only a single reduced flavin binding site. Quantum yield results demonstrate that bioluminescence requires only one reduced flavin per luciferase, ruling out mechanisms involving either two reduced flavins or one reduced flavin plus one oxidized flavin per catalytic cycle.


Intramolecular crosslinking of tropomyosin via disulfide bond formation: evidence for chain register.

Rabbit skeletal muscle tropomyosin can be crosslinked in the native state by the use of 5,5'-dithiobis(2-nitrobenzoate), which forms disulfide bonds between the two subunits. Using polyacrylamide gel electrophoresis in sodium dodecyl sulfate we have shown that this crosslinking goes to completion over a wide range of protein concentration, ionic strength, and reagent concentration. Crosslinks are not formed in denaturing solvents such as sodium dodecyl sulfate and guanidine hydrochloride despite the fact that the same number of SH groups react as in the native state (2.3 +/- 0.2). The sedimentation coefficients of crosslinked and non-crosslinked samples are identical. Thus, crosslinks are formed between corresponding cysteines on different chains of the same molecule. This provides strong evidence for a model of chain interaction with both chains in register. Evidence has also been obtained that rabbit skeletal tropomyosin is composed only of alphaalpha and alphabeta subunits rather than a random mixture of chains.


Nonribosomal proteins associated with eukaryotic native small ribosomal subunits.

The native small ribosomal subunit (Sn) from rabbit reticulocytes which is able to initiate translation of globin mRNA in a cell-free system carries additional protein components. The latter can be separated from the subunit in a high salt sucrose gradient yielding a top fraction (T) and a complex fraction (C), sedimenting at about 4 and 15 S, respectively. Polyacrylamide gel electrophoresis in sodium dodecyl sulfate revealed that fraction T contained four dominant polypeptides, while fraction C represents a large protein complex consisting of at least 10 polypeptides. Sn isolated from other sources showed similar patterns of their nonribosomal proteins. Reconstitution experiments revealed that fraction C is absolutely required for protein synthesis, while fraction T enhances protein synthesis only in the presence of C. The adherence of these protein factors to the subunit is not mediated by magnesium ions. Treatment of Sn with EDTA and centrifugation in a magnesium-free sucrose gradient caused unfolding of the subunits and dissociation of several ribosomal proteins, but not of the factors. The unfolded ribosomal subunits sedimented as two distinct peaks. The more slowly sedimenting peak contained proteins of fraction T and the faster sedimenting one contained the 15S complex, indicating heterogeneity of the Sn population with respect to the factors attached to them.


Modification of intensity and direction of electron flow across bileaflet membranes.

The intensity and the direction of electron flow across chloroplast extract bilayer membranes are modified by the presence of biliproteins. Biliproteins including C-phycocyanin, phycoerythrin, allophycocyanin, and Chroomonas phycocyanin enhance the photosensitivity of the membranes. The photoelectric spectra of the membranes in the presence of biliproteins correlate with the absorption spectra of these biliproteins. Experiments are presented to demonstrate the specific character of the electron-directing ability of biliproteins. A possible mechanism involving the interaction between the biliproteins and the membranes is proposed.


Fatty acids as modulators of membrane functions: catecholamine-activated adenylate cyclase of the turkey erythrocyte.

Activation of the adenylate cyclase [ATP pyrophosphate-lyase (cyclizing), EC 4.6.1.1[ from turkey erythrocytes by isoproterenol decreased precipitously below 26 degrees. Certain unsaturated fatty acids enhanced the activation by isoproterenol up to 25-fold at reduced temperatures. The fatty acid also enhanced the formation of a persistent active state of the enzyme which was produced by preincubation with guanosine 5'-(beta,gamma-imino)triphosphate [Gpp(NH)p]. Once the enzyme had been activated by Gpp(NH)p plus isoproterenol the reaction rate was no longer as temperature sensitive and the fatty acid had little effect. The synthetic Gpp(NH)p apparently substituted for the natural GTP, which is known to play a regulatory role in the adenylate cyclase system. The findings suggest that the function of GTP which is mediated by the hormone is the temperature-sensitive event which is enhanced by the fatty acid. The use of free fatty acid to probe membrane-associated reactions in intact cells and in isolated membrane preparations is proposed.