Comparison of antiplaque agents using an in vitro assay reflecting oral conditions.

An in vitro assay is described using saliva-treated bovine enamel slabs for determining the potential of chemotherapeutic agents to adsorb to tooth surfaces and act against plaque-forming bacteria. Chlorhexidine was found to inhibit the formation of in vitro plaque by Actinomyces viscosus, A naeslundii, Streptococcus mutans and S sanguis. Actinobolin was found to have marked antibacterial properties but limited adsorptive qualities.


Snack food intake of adolescents and caries development.

The relationship between the frequency of eating various snack foods, socioeconomic variables, and an increment in caries was studied in 143 adolescents. There were negative correlations between DMFT increments and the frequency of apples, fruit juice, and sugarless gum intake, and a positive association of DMFT increments with chocolate candy intake and spending money.


Effect of interdental flossing on the incidence of proximal caries in children.

A clinical study was designed to evaluate the effect of frequent interdental flossing on the incidence of proximal dental caries. School children from a fluoride-deficient area were studied after clinical and radiographic examinations. Each child had at least one contralateral pair of intact, contacting proximal tooth surfaces between the distal surface of the primary cuspid and the mesial surface of the first permanent molar. Randomly selected test surfaces were flossed each school day with unwaxed dental floss by researchers. The contralateral surfaces served as controls. Flossing was done for eight months, discontinued for four months, and reinstituted for another eight months. A significant reduction in the incidence of proximal caries resulted.


Sorption of water by filled-resin composites.

Water-sorption studies discriminate between passive (those containing Sn, Nb, and Ti) and reactive (those containing Zn and an alloy of CoCrMo) metal-resin composites. The reactive ones form hydrated oxides or hydroxides or both, in accord with a parabolic rate law. The nature of the chemical reaction is elucidated in two instances by analysis of the resultant gases.


Effect of packing pressure on the abrasion resistance of dental amalgams.

Three dental amalgams were investigated to determine if their abrasion resistance was significantly affected by different packing pressures. Abrasive wear tests were performed on a machine designed to test materials under conditions similar to masticatory function. The results show that the abrasion resistance of the amalgams is unaffected by the packing pressure.


Influence of certain manipulative variables on the static creep of amalgam.

The effects of trituration time on the creep of eight commercial dental amalgams was determined. The data show that trituration time does influence the creep of amalgam, but its magnitude varies from one alloy to another. The condensing procedure also influences creep.


Rheology of composite filling material pastes.

The rheology of composite pastes in the unset state has been studied using a cone and plate viscometer. All materials behaved as Bingham bodies, exhibiting linear shear stress-shear rate plots, with a positive shear-stress intercept (the yield stress of the material). The shape of the plot gave the coefficient of viscosity of the material; at sufficiently high shear rates, shear failure occurred, marked by a breakdown of the linear relationship. The materials studied gave a very wide range of the various rheological factors.


Tonometric measurement of dental pulpal and mandibular marrow blood pressures.

Dental pulpal and mandibular marrow vascular pressures were studied with a tonometric method under conditions of autoperfusion and step flow controlled perfusion. The tonometric pulpal and marrow pressures averaged 17 +/- 5 mm Hg and 20 +/- 6 mm Hg, respectively. The venous end pressure was 16 +/- 8 mm Hg at a perfusion pressure of 156 +/- 28 mm Hg. The tonometric pulpal pressures were lower and were less variable than the comparable canulation pulpal pressures.


Duration of the electromyographic silent period following the jaw-jerk reflex in human subjects.

During voluntary jaw clenching, a sharp tap to the menton of the mandible resulted in a transitory silent period (pause) in the electromyographic activity of the masseter and anterior temporalis muscles. Factors that could influence the duration of the silent period were studied, including direction and magnitude of the stimulus applied by the operator, the amount of muscular effort exerted by the subjects, and varying occlusal vertical dimensions. Decreased isometric muscle force resulted in statistically significant increases in silent period durations.


Effects of GK-101 (NMG) and sodium hypochlorite on salivary amylase activity.

A study was designed to assess the effects of the sodium salt of N-monochloroglycine (NMG) and sodium hypochlorite on the activity of salivary amylase. Concentrations of each agent were varied to determine the concentration at which the threshold and total inhibition of enzyme would be obtained. The data indicated that NMG at concentrations of 0.10% (w/v) does not affect amylase activity, whereas sodium hypochlorite at concentrations of 0.05% (w/v) totally inhibits salivary amylase activity.


Lack of effect of excess glucocorticoid hormone on the rate of dentin deposition in rats.

A study was undertaken to determine the effect on the rate of deposition of dentin when high levels of adrenal glucocorticoid hormone are administered to rats. The results indicate that in the hypercorticoid rat, despite an increased eruption rate and a reduced width of incisor wall, no alteration occurs in the rate of dentin formation.


Gastrointestinal absorption studies in cardiac cachexia.

The nutritional status of 11 patients with severe mitral valve disease was investigated pre-operatively and 3 months post-operatively. It was shown that they were malnourished pre-operatively, and that this appeared to be related mainly to anorexia.


Enamel biopsy results of children receiving fluoride tablets.

This study measured the fluoride in tooth enamel of 338 schoolchildren after daily use of acidulated phosphate-fluoride (APF) tablets, and investigated the relationship between observed amounts of enamel fluoride and incidence of caries. Randomly selected study groups received under supervision either one placebo tablet, one APF tablet containing 1 mg fluoride, or 2 APF tablets (3 hours apart) each school day. An abrasive enamel-type biopsy of a maxillary central incisor was taken 30 months after the start of fluoride tablet treatments at the time of the follow-up examinations. Mean fluoride levels in the biopsied enamel from each of the three groups were similar despite a significant restriction in caries in the group receiving two APF tablets per day. These findings suggest that fluoride can restrict dental caries by some mechanism other than fluoride uptake in the enamel.


Patients of record.

Although the case of Smith vs Jones helped settle some of the problems in defining patients of record, it did not address itself to all the situations in which a definition of patients of record would be needed. The question of which dentist should have the records of certain patients will present difficulty as long as two or more dentists continue to practice without a formal agreement that addresses this question. And the rights of partners, associates or employees should be determined in writing in the partnership agreement, employment contract, or bylaws of corporate practice before the association is established.


Paul-Bunnell antigen in lymphoma and leukemia spleens.

Lymphoid cells obtained from spleens of patients with lymphomas or leukemias were studied for the presence of heterophile (Paul-Bunnell (P-B)) antigen. A mixed agglutination (MA) test was established utilizing monolayers of cells attached to poly-L-lysine-coated wells of plastic U plates. After incubation of the monolayers with infectious mononeucleosis (IM) sera, indicator cells, sheep, or trypsinized bovine erythrocytes were added. The results were assessed according to sedimentation patterns of the indicator cells on the monolayers. Positive MA reactions were shown to be due to specific binding of P-B antibodies to the corresponding antigens on the spleen cells. Positive results were obtained with 15 of 37 spleens from patients with Hodgkin's disease, 5 of 8 lymphoma spleens, 4 of 15 chronic myelocytic leukemia spleens and 2 of 4 chronic lymphocytic leukemia spleens. Only 2 of 25 spleens from patients with various other diseases and 1 of 26 apparently normal thymus specimens gave positive results. This study confirmed demonstration of P-B antigen in lymphoma and leukemia by means of absorption experiments, which was reported previously.


Platelet-cancer cell interaction in metastasis formation: a possible therapeutic approcach to metastasis prophylaxis.

The mechanism of the early stage of metastasis formation by sticky blood-born cancer cells is discussed. Abnormal platelet aggregation to circulating and lodged cancer cells, as well as alterations of blood coagulation and fibrinolysis play an important role. The reducing effect of several platelet aggregation inhibitors on cancer cell stickiness and tumor embolism mortality has been investigated in rats after intravenous transplantation of 1 X 10(6) Walker-256 carcinosarcoma cells. The tested substances diminished platelet aggregation to circulating cancer cells, leading to a dose-dependent inhibition of cancer cell lodgment to the endothelium. Furthermore, some of the substances prevented lethal pulmonary tumor cell embolism which was observed in 60% of the controls. These results are interpreted by assuming an inhibition of disseminated intravascular coagulation which occured after intravenous transplantation of Walker-256 carcinosarcoma. On this basis a clinical long-term study for metastasis prophylaxis was started more than 4 years ago with one of the tested substances, the dipyridamole derivative RA 233, in 40 patients with sarcoma or malignant lymphoma of the head and neck region. The provisional results obtained in matched pairs are discussed.


Preliminary clinical study of prednimustine in lung cancer.

Prednimustine is a prednisolone ester of chlorambucil which has been found effective in a variety of tumors. Eleven patients with advanced carcinoma of the lung (5 adenocarcinoma, 3 squamous cell carcinoma, 2 small cell carcinoma and 1 large cell carcinoma) were treated at a dosage of 40 mg. per day. Nine had previously failed on combination chemotherapy. No objective responses were observed. Leukopenia or thrombocytopenia were found in 4 patients with nadirs of 2,000 WBC and 60,000 platelets. The lack of response may be a function of the inability of lung carcinoma to concentrate the drug as shown with radioactive labeled Prednimustine. The malignant cells may lose their glucocorticoid binding capacity normally present in the lung. Determination of glucocorticoid binding capacity or Prednimustine uptake might predict the effectiveness of Prednimustine in the treatment of tumor. Prednimustine was well tolerated and may be given safely in advanced malignancies. Further studies with high intermittent doses and selection of tumors with steroid binding properties are now in progress.


Effects of the simultaneous administration of diethylstilbestrol and prednisolone on serum enzymes in Duchenne's muscular dystrophy.

The effects of diethylstilbestrol (DES) and prednisolone (Pr), administered alone or in combination, on the serum enzyme activities in Duchenne's muscular dystrophy (DMD) have been evaluated. When DES and Pr were given simultaneously to four boys with DMD, the mean creatine phosphokinase and lactate dehydrogenase levels fell to about one half those achieved with either agent alone. No untoward or unexpected side effects were encountered. These observations, and our previous demonstration that both agents reduce enzyme efflux from skeletal muscle, give promise that a safe combination therapy may be found to approximately normalize the serum in DMD. This will permit us to test the hypothesis that lowering the serum enzymes, by reducing their loss from skeletal muscle, will slow or arrest the muscle deterioration characteristic of this disease.


Giant platelets and thrombocytopenia: a bleeding disorder in siblings. Clinical laboratory and electron microscopic aspects.

This report presents the findings of an inherited platelet abnormality in two members of the same family. The authors tested hemostasis of six normal and two abnormal members, studied the platelets using optical and electron microscopy, and genetic transmission in the family. The literature is also reviewed.


Serotonin and monoamine oxidase in mouse skin: effects of cigarette smoke exposure.

Mice were exposed to either air or cigarette smoke and the content and uptake of serotonin and activity of monoamine oxidase were determined. Serotonin concentration increased as a function of the frequency of exposure, while serotonin uptake by the skin was maximally increased after two 8 min. exposures. MAO activity for serotonin, but not for tyramine, was decreased by cigarette smoke exposure of more than 8 min.


Preparation areas resisting displacement of artificial crowns.

The areas of luting cement resisting rotation of artificial full crowns subjected to non-axial forces were calculated for varying values of preparation diameter, height, and convergence angle. The calculations were performed for regular conical and pyramidal preparations. The results showed that the resisting areas are larger in pyramidal than in conical preparations. Increasing the convergence angle resulted in an almost linear reduction in resisting area. The reduction was particularly pronounced for preparations of large diameters.


Occlusion between removable dentures and natural teeth.

Study casts on thirty-five partially edentulous patients were analysed at their arch level and at the interarch levels. At the arch level the crest of the residual ridge is located lingually to the position of the remaining teeth in the maxilla as well as in the mandible. The spatial interarch relationship between the residual edentulous ridge and the antagonist natural teeth in the buccolingual plane indicated that the crest of the residual ridge is lingual to the occlusal surfaces of the antagonist teeth. In the maxilla the positioning of the artificial teeth in the area previously occupied by the natural extracted teeth will place the denture teeth far buccal as well as away from the crest of the residual ridge. Other possibilities are to place the artificial teeth in a cross bite relation or to eliminate the buccal cusps of the replacement teeth. In the mandible the denture teeth can be placed at the position occupied formerly by the natural teeth.


Assessment of the quality of restorations. A literature review.

Most assessments of the quality of restorations are entirely subjective and involve standard clinical diagnostic equipment. However in recent years there has been an increasing demand for more accurate and reliable methods. Attempts to achieve these have been directed mainly towards the standardization of clinical judgements by the provision of various systems of guidelines of criteria upon which to base them. While these have improved the usefulness of the assessments, they have remained largely subjective. Furthermore, the efficacy of using the particular criteria selected are themselves open to questioning. By the use of more complex methods of examination, often in the field of restorative materials research, assessments have been made of various features of restorations and a body of knowledge concerning factors that might influence or manifest their quality has been build up. However the true significance of much of this knowledge in terms of the clinical behaviour, and thus the finite quality of restorations in service, has yet to be established, for many of the studies have been undertaken in isolation from the dynamic conditions of function in the mouth. Notably, however, a few objective clinical studies have been carried out and objective measurements of some factors affecting the quality of restorations have been reported.


Kinematics of the tooth tapping movement.

Electrical activity in the masseter muscles and tooth contact vibrations were recorded simultaneously from subjects tapping their teeth slowly into maximal intercuspidation and again with maximal frequency. High speed cinephotography was also used with four of the ten subjects. Three main parts could be distinguished on the obtained graphical representation of the tooth tapping movement: tooth contact phase (TCP), opening phase (OP) and closing phase (CP). Tapping frequency was increased by decreasing the jaw opening degree and the durations of TCP, OP and CP. The jaw velocity immediately before tooth contact, which may be of significance for the reflex response, was however not increased. The average jaw speed was nevertheless increased from 10 to 15 cm/s since the turning from OP to CP was more abrupt in high than in low frequency tapping. The duration of electrical activity after tooth contact was significantly shorter at tapping with high than with low frequency. The teeth maintained contact without detectable rebound between each open-close cycle. The OP started about 100 ms after the cessation of electrical activity both at low and high tapping frequency. The time between end of electrical activity and the start of a new OP was supposed to be dependent upon the relaxation time of the masseter muscles.


The in vitro measurement of amalgam corrosion rates by the polarization resistance technique.

Measurement of the corrosion rates of three distinctive amalgam alloys (lathe-cut, spherical and dispersed-phase) when immersed in three different electrolytes, including saliva, is reported. The results indicate that the dispersed phase alloy amalgam exhibits a lower corrosion rate than a conventional lathe-cut alloy amalgam but is somewhat inferior to a spherical alloy amalgam.


Evoked EMG of masseter and temporal muscles in man.

Following a percutaneous stimulation on the mandibular notch skin, two kinds of responses were recorded in the ipsilateral masseter and temporal muscles in man. The two responses had their proper stimulating points. The early response appeared with about a 2 ms latency and the late one with about a 6 ms latency which was shorter than that of T wave of the same muscle by about 1 ms. No responses were induced in the contralateral masseter and temporal muscles. Regarding the recovery process of the late response following double stimuli, a testing late response was released about 100% from the effect of conditioning shock at a longer interval than 80 approximately 95 ms. It might be safe to consider that the previous assumption, i.e. those two responses seemed to be M and H waves respectively, had been fortified. H response evoked in muscles tested seems to be sensitive enough to show the difference between excitatory states of its reflex arc.


Ecologic changes in the oral cavity caused by removable partial dentures.

1. The introduction of a removable partial denture into the oral cavity adversely affects the prevailing ecologic situation in terms of plaque formation. 2. The rehabilitative effect of a removable partial denture may be safeguarded by controlling plaque formation by strict personal hygienic measures on the part of the patient. In particular, proximal surfaces adjacent to denture bases should be pointed out to patients as surfaces to which they must give special attention. 3. Simplification of the design of removable partial dentures can reduce their damaging potentialities. 4. Further prophylactic measures, such as topical application of fluorides and perhaps other chemicals, should also be taken.


Scanning electron microscope study of marginal adaptation of amalgam in restoration finishing techniques.

Voids and gaps between the surfaces of the amalgam and the cavity preparation were apparent in the carved and the polished samples. These spaces in the burnished specimens were filled with an amorphous bulk of amalgam apparently caused by the burnishing process. Since the margins of burnished amalgam restorations have been shown to leak less than those of carved and polished specimens, it is hypothesized that this is due to the improved marginal adaptation attained through the burnishing process.


Effect of a carious dentin softener on the dentin and pulp.

The application of GK-101 to carious dentin softens the first or outer layer which contains denatured collagen. The second or inner layer of carious dentin, containing normal collagen fibers, is unaffected. The pulps of dog teeth were not affected by applying the solution to freshly prepared sound dentin.


Biologic laws governing functions of muscles that move the mandible. Part III. Speed of closure--manipulation of the mandible.

The character of the occlusal surfaces of teeth programs the functions of muscles that move the mandible and imposes specifications upon the dentist within which he must work in manipulating the patient's mandible. If he exceeds those specifications, protective responses that inhibit his efforts are elicited in the patient's musculature. A knowledge of the laws governing functions of the muscles that move the mandible enables the dentist to acquire mandibular-manipulation skills necessary for diagnosis and effective occlusal treatment. A model in which the dentist visualizes the patient, the patient's protective reflexes, the components of the patient's gnathostomatic system, and himself as four independent personalities participating in the jaw manipulation is a useful tool in acquiring mandibular-manipulation skills. This article is Part III of a series presented in four parts on the "Biologic Laws Governing Functions of Muscles That Move the Mandible."


Characteristics of temporomandibular joint problems.

A review of the characteristics of 145 patients with temporomandibular joint and myofascial pain-dysfunction syndrome is presented. The material includes both temporomandibular and myofascial involvements. The evidence supports the psychophysiologic etiology theory for most patients. This does not exclude anatomic abnormalities which may be present in such patients nor anatomic abnormalities which may be present without psychogenic causes. The lack of awareness of the range of condylar movement is contributory to iatrogenic trauma. A classification of etiologic factors is proposed. The superimposition of one upon another can create a severe problem. The superimposition of two upon a third can create an unusually severe problem.


Effects of supervised daily dental plaque removal by children: II. 24 months' results.

After two school years of a supervised daily plaque-removal program in school, children in the treatment group showed a significant reduction in plaque and gingival inflammation scores compared with children in the control group. However, differences between groups in terms of plaque and gingivitis scores virtually disappeared during the summer vacation. The increment of dental caries was lower in the treatment group than in the control group, but the reduction, which averaged about 20 percent, was not statistically significant either for teeth or for surfaces. Although the 24-month findings of the present study indicate some degree of success in reducing plaque and gingivitis and a marginal effect in reducing the incidence of dental caries among children who engaged in daily, supervised plaque-removal in school, obvious drawbacks limit the value of this regimen.


Expenditures for the dental care of indigent children in the Chattanooga project, 1971-1975.

This paper is part of a continuing study of the cost of children's dental care in a publicly funded model program. The Program--the Chattanooga Project--was designed to provide information and experience necessary for the development of similar programs elsewhere in the United States. From 1970 to 1975 comprehensive dental care was provided, at no charge, to an average of 5,500 indigent children per year. Children were treated in private practices (39%), public fixed clinics (20%), and public mobile clinics (41%). Costs were defined as public expenditures for purchasing care from private practitioners or producing care in public practices. As a framework for the analysis, program activities and their respective costs were divided into direct and indirect components. The former relate to the provision of care and the latter to noncare-oriented activities. Direct (indirect) costs per patient were $46.56 ($16.31) in private practices, $40.17 ($16.11) in fixed clinics, and $35.49 ($13.41) in mobile clinics. These results substantiate previous findings from a shorter period. A priori reasons for differences among the three modes in terms of patients' health status or the type of care provided have been specified and are currently under investigation.


The cost of providing restorative dentistry in an alternative delivery mode.

This study is based on the Forsyth Dental School experiment, where it was shown that dental hygienists can be trained to perform restorative dental functions which are now the exclusive responsibility of dentists. The focus of the Forsyth study was to determine the length of training time required and to measure the qualitative and quantitative aspects of services carried out by the hygienists. As a follow-up to that study, this paper is concerned with the economic aspects of the personnel substitution suggested by the Forsyth project. The basic hypothesis of the study is that there would be a considerable gain from this change, and that this gain can be measured by estimating the costs of operation in the new setting anc comparing them to costs in the conventional setting. Combining estimated clinic costs and productivity data provides a measure of the per-surface supply price for an amalgam restoration. This estimate is 44 percent lower than usual fees and 29 percent lower than current welfare fees. The magnitude of this difference implies that the introduction of Forsyth clinics would lead to considerable economics in the elivery of these services.


[Degenerative retinal conditions after treatment with Busulfan during pregnancy (author's transl)].

A patient with chronic granulocytic leukemia was treated with Busulfan for the three last months of pregnancy. The infant appeared normal except for an atypical tapetoretinal degeneration. We studied the other cases in the literature. All pregnancies produced an apparently normal infant although three infants were small. The case of Diamond had microphthalmia. We conclude that Busulfan is perhaps toxic to fetal retina.


[Hodgkin's disease during remission of acute lymphoblastic leukemia (author's transl)].

1 1/2 years after diagnosis of acute lymphoblastic leukemia, Hodgkin's disease, stage IIA of cervical lymphnodes could be verified microscopically in a 7 year old girl in continuous complete remission (of leukemia) and was treated with regional irradiation and combination chemotherapy after exploratory laporotomy with splenectomy. The patient now is off therapy, healthy and without any signs of relapse of the two malignancies.


[Clinical significance of cationic proteins of leukocyte lysosomes: cationic leukocyte antigen (CLA) as a marker of blast crisis in chronic myelocytic leukaemia (author's transl)].

Cationic leukocyte antigen (CLA) was estimated in urine of acute and chronic leukaemics using quantitative immuno-precipitation techniques. The studies demonstrated that CLA is a marker of the (myelo-) blast crisis in patients with chronic myelocytic leukaemia (CML). By these studies the value of the determination of CLA for the differential diagnosis of acute myeloblastic leukaemia versus initial (myelo-) blast crisis in CML and the lymphatic leukaemias, respectively, was evident. The terminal blastic transformation in CML was indicated early by an elevation of the urinary CLA-level. The blast-crisis was accompanied by a heavy CLA-uria. The results are documented by demonstration of special studies of characteristic cases and discussed in the light of recent results of immunological and cytochemical findings on the nature of blast crisis in CML.


Histopathological study of regional lymph nodes in osteosarcoma.

This paper presents the histological appearance of the lymph nodes in cases of osteogenic sarcoma of the limb bones. The nodes were studied for the degree of sinus histiocytosis. Cases with no sinus histiocytosis showed a poor prognosis while cases with moderate to marked sinus histiocytosis showed a better rate of survival. Since the regional lymph nodes play an important part in the immunological process, preservation of regional nodes is suggested.


Paget's sarcoma in Tasmania.

Six proven cases of Paget's sarcoma occurred in Tasmania in the decade 1965 to 1974. The incidence was 0-16 cases per 100,000 population per year. The sex ratio was two male: one female. The average age was 61-2 years. All cases occurred in the pelvis or adjacent femur. Average time of survival after onset of symptoms was one year. Two patients had lymph node metastases. One patient had no pulmonary metastases; a further patient may have had no pulmonary metastases. All patients were born in Australia (State of Tasmania) of predominantly Anglo-Saxon stock.


[Juvenile type of chronic myelogenous leukemia in a 3 6/12 year old boy with trisomy 21 mosaicism but no symptoms of Down's syndrome (author's transl)].

In a 3 6/12 year old boy, with the juvenile type of chronic myelogeneous leukemia cytogenetic examination of bone marrow and blood, performed two months before onset of the acute blastic crisis, showed two cell lines: the first one with a normal karyotype 46, XY and the second one with a trisomic karyotype 47, XY, +21. This finding of a mosaic trisomy 21 in a patient without symptoms of Down's syndrome allow to assume the trisomy cells to be malignant, and the type of mosaicism to be proliferative. This karyologic finding could be taken for an early prognostic, unfavourable sign of the disease. The significance of karyologic examination with exact classification of atypical leukemias is stressed.


Planimetric evaluation and comparison of roentgenograms of osteogenic sarcomas induced by 226Ra and 224Ra in mice.

Osteosarcomas were induced in mice by three activities of 226Ra (8.8 micronCi, 24.6 micronC and 70.5 micron Ci/kg) and by three activity levels of 224Ra administered in fractionated doses during a period of 75 weeks (total activity per mouse: 0.65 micron Ci, 1.88 micron Ci). In the 226Ra series 74 cases and in the 224Ra series 89 cases of osteosarcomas were evaluated by means of planimetric measurements of roentgenographic images, including the calcified structures. Even though it is not possible to differentiate the series precisely, still some differences between tumors under study could be found. In comparison with 226Ra series, the sarcomas induced by 224Ra are in average rather larger, calcified stuctures appear not to be fully developed and differentiated, he anatomical distribution is different from that characteristic to the 226Ra induced tumors, the mean life span is shorter. It is quite likely that not only the incidence but also some of the features of osteosarcomas are dependent on the time and tissue distribution of the dose delivered.


Nephrotoxicity associated with combined gentamicin-amphotericin B therapy.

The administration of a low total dose of amphotericin B to four consecutive patients already receiving gentamicin resulted in a deterioration of renal function in all. No other cause of the renal dysfunction was apparent in three cases. It appears probable that these drugs exhibit synergistic nephrotoxicity.


Retinoblastoma and osteogenic sarcoma.

Radiogenic and non-radiogenic osteosarcomas are rather frequent in retinoblastoma patients and probably also in retinoblastoma families. Besides the pathologic gene for retinoblastoma, there must be a predisposition to develop osteogenic sarcomas, which is probably genetic.


Cephalic kinetics of intra-arterially injected lidocaine.

The intravenous injection of 3 mg./kg. of lidocaine into the facial artery resulted in internal carotid artery blood levels between 5 and 7 microgram/ml. 15 seconds thereafter. Internal and external jugular vein blood levels exceeded 30 microgram/ml. at the same time. When the same amount of lidocaine was injected into the facial vein, carotid blood levels were less than 3 microgram/ml., peaking at 30 seconds. Concentrations of the local anesthetics in the jugular vein peaked at 15 seconds, exceeding 35 microgram/ml. The feasibility of local anesthetic drugs reaching the cerebral circulation through a retrograde pathway was indicated, suggesting that this mechanism may be the route for some of the untoward reactions observed after the injection of local anesthetics in the head and neck area.


Vestibular extension with xenogenous fascial grafts.

Fascia obtained from the abdominal wall of a rat was transplanted to the oral cavity of five dogs as a graft material for vestibular extension. In all five dogs the grafted fascia remained in place as the surgical defects were covered with epithelium, which transpired within a period of 4 weeks. After 6 months, the vestibular depth was increased significantly and the vestibule was smooth and regular.


Biopsy technique for fibro-osseous and osteolytic lesions of the jaws.

A biopsy technique is presented for obtaining small tissue samples from fibro-osseous and osteolytic lesions which are not readily accessible for surgical biopsy. Trephine burs and a nonaspirating biopsy needle may be utilized for obtaining adequate tissue from fibro-osseous and osteolytic lesions for frozen section and routine histopathologic examination.


Garré's osteomyelitis of the mandible. Report of a case.

A case of Garré's disease has been reported. This case is atypical in that the patient presented with only a periosteal bone mass and a negative history of toothache, abscess, or trauma to the area. Because of this, diagnosis was not possible without microscopic examination. Atypical cases of this nature cause diagnostic problems, and several disease states must be considered in a differential diagnosis. These include the following: 1. Ewing's sarcoma, which also occurs in this age group and may show cortical reduplication on radiographic examination. The prognosis in cases of Ewing's sarcoma is poor, and death may occur in a matter of weeks. 2. Infantile cortical hyperostosis (Caffey's disease), which is characterized by development of soft-tissue swelling and cortical thickening of the mandible. The disease runs a benign course and regresses without treatment. 3. Osteogenic sarcoma, which occurs in slightly older age groups but presents as a cortical expansion with facial deformity. The disease is highly malignant and carries a poor prognosis.


The incidence and relationship of the lateral ramus prominence to the mandibular foramen.

A study was undertaken to determine the incidence of the lateral ramus prominence and its relationship to the mandibular foramen. The lateral ramus prominence, as determined by inspection and palpation, was identified on both the right and left rami of all specimens. Bilateral measurements were made on fifty randomly selected adult dentulous mandibles. Significant correlation coefficients were obtained for all measurements between right and left rami. Therefore, either the left or right side measurement for each parameter was selected at random, and the data were subjected to statistical analysis. The lateral ramus prominence varied from 4.7 mm. anterior to 4.7 mm. posterior to the foramen, and from 0.9 mm. to 16.2 mm. superior to the foramen. It was located anterior to the foramen 66 per cent of the time.


Vitamin E and periodontitis in the rat.

This investigation was designed to study the effect of vitamin E on the course of periodontitis in thirty-six adult male albino rats. The rats were divided into three groups of twelve and placed on test diets which consisted of pelleted feed that either was deficient in, or contained adequate and high amounts of, vitamin E. After the animals had been on their respective diets for 8 weeks, a local irritant in the form of a stainless steel wire was placed around the maxillary left second molar of each animal. The wire served both as a mechanical irritant and as a collector of plaque and debris. Six weeks after the wire was placed, the animals were killed and the periodontium was examined histologically. Migration of the epithelial attachment, alveolar bone level, and numbers of inflammatory round cells were then evaluated on both sides of the maxilla. Multivariate analysis of variance was used to determine significant difference in the parameters. The results of this experiment indicate that a deficiency of vitamin E does not cause increased destruction of the periodontium in the presence of periodontitis. Moreover, no beneficial effects from the therapeutic use of vitamin E to combat periodontitis were found.


The oral melanotic macule.

A clinical and histologic study of eighty oral melanotic lesions which do not readily fit into recognized categories of melanotic lesions was conducted. These lesions tend to occur in the fifth decade of life and are most frequently seen on the gingiva, with the buccal mucosa and palate the next most frequent sites. The lesions are usually single, smaller than 1 cm., but they may also occur as multiple lesions. There is no sex bias, and there seems to be a number of etiologic factors. In a few cases long-term follow-up was possible. There is no indication of a tendency toward recurrence or development of malignant lesions. Histologically, none of the lesions shows atypia. Melanin pigmentation tends to be present in significant amounts in the basal-cell layer and less often in the lamina propria. There are no outstanding histologic differences among the eighty specimens. It is suggested that the term oral melanotic macule be used for these lesions, unless a specific cause can be confirmed by clinical data. Although these lesions should not be considered premalignant, it would be prudent to remove them for histologic confirmation of clinical impressions.


Histopathologic, ultrastructural, and immunologic findings in an oral psoriatic lesion.

There has been some controversy over whether psoriasis can involve the oral mucosa. An oral lesion in a 32-year-old man with a psoriatic scalp lesion has been studied by light and electron microscopy and by immunologic methods. Results from each of these three techniques are consistent with previous findings in psoriatic lesions and suggest that oral psoriasis can occur.


Sebaceous choristoma of the thyroglossal duct.

The presence of sebaceous glands within the oral mucosa is not uncommon. Such Fordyce granules are frequently seen on the buccal mucosa and lips, as well as in the retromolar area, gingiva, and palate. Whereas sebaceous elements are rarely encountered on the tongue, three cases of ectopic sebaceous glands have been reported in association with apparently patent thyroglossal ducts. An interesting case of a previously unreported sebaceous choristoma of the thyroglossal duct is described.


Intraoral melanocytic cellular nevi.

Eight cases of intraoral melanocytic cellular nevi are presented, together with the clinical features and limited follow-up information. These cases are added to those already published, so that a meaningful series may eventually be analyzed.


Taurodontism, short roots, and external resorption, associated with short stature and a small head.

This article describes a patient who exhibited taurodontism, relatively short roots, external resorption of the roots of the anterior teeth, and a marked tendency toward microcephalic dwarfism. This case is similar to that reported previously by Sauk and Delaney.


Squamous-cell carcinoma in a residual mandibular cyst.

Described is a case of squamous-cell carcinoma arising in a residual cyst in a 60-year-old edentulous woman. The clinical and radiographic diagnosis was residual cyst, and the treatment employed was conservative surgical enucleation. The cause of these changes is unknown. Theoretically, the inflammatory reaction may have been a predisposing factor.


Villonodular synovitis with synovial chondromatosis.

Pigmented villonodular synovitis and synovial chondromatosis are uncommon benign lesions involving the articular surfaces of diarthrodial joints. Reported is a case of a benign synovial lesion of the temporomandibular joint, which was clinically thought to be a malignant parotid compartment tumor, showing histologic features of both pigmented villonodular synovitis and synovial chondromatosis. A review of the literature reveals a single case in which cartilaginous bodies were found in the joint; however, the synovial tissue showed features of only villonodular synovitis, with no mention of cartilaginous foci.


Simple metallic compounds as pulp-capping agents. A pilot study.

A pilot study is described in which the exposed pulps of molar teeth of normal laboratory rats were capped with various metallic compounds in general medical usage. There appeared to be no relationship between the response obtained and the pH of the compounds studied. Aluminum powder, aluminum hydroxide, Aludrox, aluminum oxide, light magnesium oxide, magnesium hydroxide, and titanium dioxide gave poor results. Barium sulfate, calcium carbonate, cupric oxide, ferric oxide, heavy magnesium oxide, and stannic oxide merited more detailed study.


Polyethylene tubes as a model for the root canal.

Polyethylene tubes, closed at both ends with casting wax and with four perforations in the middle, were implanted subcutaneously in rats and evaluated as a research model simulating the root canal. As controls, wax bars and unperforated tubes were implanted. Attention was given to the reaction of the tissue surrounding the perforated empty tube, the tissue reaction to polyethylene and casting wax, and to the displacement of the tubes.


Effectiveness of root canal irrigation.

When root canals are being enlarged, repeated irrigation is mandatory. Under the conditions of this study, the most significant factor in obtaining maximum results in root canal irrigation is the diameter of the canals. The removal of debris seems to be a function of canal diameter rather than the type of solution used.


Radiation exposure and distribution measurements for three panoramic x-ray machines.

1. Exposures to internal sites in the phantom varied as follows: Panorex, 0.3 mr to 2.4 r; Orthopantomography, 0.4 mr to 0.8 r; Panelipse, 0.2 mr to 1.4 r. 2. With the phantom exposed for a normal-density radiograph at 65 KVP, the average radiation exposure at the sites measured were for the Panorex, Orthopantomograph, and Panelipse respectively: 8, 13, and 4 mr at the pituitary gland; 22, 62, and 8 mr at the superior area of the parotid gland; 13, 8, and 5 mr at the thyroid gland; 343, 425, and 365 mr at the submaxillary gland; and 50, 154, and 272 mr at the base of the tongue. 3. External exposures to the phantom and patients were found to be in good agreement at the low KVP. At the high KVP (using patients who were larger than the phantom), exposures at lateral and posterior sites showed relatively good agreement between phantom and patients, while exposures at anterior sites were less in patients. 4. The average stray radiation measurement at 1 meter from the phantom during pantomography with the three machines was 0.125 mr per exposure cycle. Individual averages were: Panorex, 0.10 mr; Orthopantomograph, 0.13 mr; and Panelipse, 0.15 mr.


New device to quantitate alveolar bone loss.

The advantages of the device described here are that (1) it produces sharp grid outlines on the film that can be accurately measured, (2) distortion factors can be compensated so that an accurate measurement can be obtained of any bony changes, and (3) the patient is exposed to radiation only once and two films are produced with and without the grid.


[Exposure to mercury in public dental clinics in Oslo--an occupational hazard evaluation].

To evaluate the occupational hazard in use of mercury by dentists, the work environment and procedures of 22 dentists and their 33 assistants were surveyed. Determinations were made of a) the mercury vapour concentrations in the offices b) the urinary excretion of mercury by the 55 persons concerned c) the mercury concentration in blood. In three of the offices surveyed, mercury vapour concentration exceeded the threshold limit value of 0.05 mg/m3, implying a lack of care in handling mercury. Urinary mercury contents of one dentist and four dental assistants exceeded 0.05 mg/l i.e. the upper "normal" value for a population with no known exposure to mercury. The manner in preparation and handling of the amalgam were considered to be the predominant comtamination factor.


Cerebromeningeal localizations in acute myeloblastic leukemia of the adult. Clinical and pathological study of 15 cases.

68 consecutive adults were treated for acute myeloblastic leukaemia (A.M.L). Involvement of the central nervous system (CNS) developed in 15 cases. The clinical characteristics of nine of these patients were: symptoms of increased intra-cranial pressure in 5, cranial nerve lesions in 4, peripheral nerve lesions in 5, cord compression in 1, hemispherical symptoms in 7. Lumbar puncture vas performed systematically on seven patients, two of them with evidence of meningeal leukaemia (M.L.). Post-mortem examination was performed on seven patients who died during the first induction treatment: three had evidence of C.N.S. involvement. M.L. developed in three patients during complete hematologic remission (R.C.) In patients younger than 60 years old, the incidence of M.L. was 8/24 (approximately 33%). Medial survival time was reduced:8 months in cases with M.L., compared to 13.5 months. Cerebro-fluid protein levels were increased in six cases without blast cells: in four cases, M.L. occurred within a few months. The frequency of meningeal leukaemia in A.M.I. is under-estimated. Eradication of this frequent complication is difficult. Prophylactic meningeal treatment may be instituted for patients younger than 60, to reduce the incidence of M.L. and to improve the median remission time.


[Does blastic crisis as revealed in chronic myeloid leukemia simulate either acute primary leukemia or acute primary leukemia with Philadelphia chromosome?].

In ten cases of apparently primary acute leukaemia, the discovery of a Philadelphia chromosome at routine examination of the caryotype led a diagnosis of blastic crisis of chronic myeloid leukemia. The clinical, cytological and cytogenetic pictures varied and only routine caryotypic examination may be used in reaching the diagnosis. The prognosis appear to be less bad than in blastic crises occurring after a long course of chronic myeloid leukaemia and closer to that of primary acute myeloid leukaemia.


Arrangement of water molecules in cavities and channels of the lattice of [Phe4Val6]antamanide dodecahydrate.

The synthetic, biologically active, [Phe4Val6] analog of natural antamanide has been crystallized from a solution containing calcium nitrate, acetone, and acetonitrile. The crystal does not contain any Ca2+ ions but does contain 12 water molecules per peptide molecule. The conformation of this dodecahydrate is identical to the trihydrate crystallized from n-hexane/methyl acetate. The packing in both crystals is very similar, governed by parallel bands of phenyl and pyrrolidine ring stacking and by continuous channels for the solvement molecules, water in this case and n-hexane/methyl acetate in the previous study. The two structures are not ideally isomorphous, since the c cell parameter differs by more than 1.0 A in the two cells. There are three functions for H2O molecules: the three intrinsic H2O molecules in the interior of the peptide ring, the H2O bound to the exposed C=O groups, and the H2O molecules that fill space in the solvent channels. There are no direct hydrogen bonds between neighboring peptide molecules and there are only two intramolecular NH-O=C bonds (of the 5 leads to 1 type).


Magnetic properties and structure of oxyhemoglobin.

A review of the published evidence reinforces the conclusion reached by Pauling and Coryell in 1936 (Proc. Natl. Acad. Sci. USA 22, 210-216) that oxyhemoglobin in blood or in solution at 20 degrees has zero magnetic moment and fails to support a recent contradictory suggestion based on magnetic susceptibility of frozen samples at temperatures below 250 K. Predicted values of bond lengths and bound angles for carbonmonoxyhemoglobin and oxyhemoglobin are given.


Kinetics of hemoglobin-carbon monoxide reactions measured with a superconducting magnetometer: a new method for fast reactions in solution.

A new technique for measuring fast reactions in solution has been demonstrated. The changes in magnetic susceptibility during the recombination reaction of human hemoglobin with carbon monoxide after flash photolysis have been measured with a new high-sensitivity instrument using cryogenic technology. The rate constants determined at 20 degrees (pH 7.3) are in excellent agreement with those obtained by photometric techniques [Gray, R.D. (1974) J. Biol. Chem. 249, 2879-2885]. A unique capability of this new method is the determination of the magnetic susceptibilities of short-lived reaction intermediates. The magnetic moment of the intermediate species Hb4(CO)3 was found to be 4.9+/-0.1 muB in 0.1 M phosphate buffer by partial photolysis experiments. This value agrees with the predictions of two-state allosteric models of cooperativity in hemoglobin. Possible applications and improvements in this technique are discussed.


Sequence specificity of mutagen-nucleic acid complexes in solution: intercalation and mutagen-base pair overlap geometries for proflavine binding to dC-dC-dG-dG and dG-dG-dC-dC self-complementary duplexes.

The complex formed between the mutagen proflavine and the dC-dC-dG-dG and dG-dG-dC-dC self-complementary tetranucleotide duplexes has been monitored by proton high resolution nuclear magnetic resonance spectroscopy in 0.1 M phosphate solution at high nucleotide/drug ratios. The large upfield shifts (0.5 to 0.85 ppm) observed at all the proflavine ring nonexchangeable protons on complex formation are consistent with intercalation of the mutagen between base pairs of the tetranucleotide duplex. We have proposed an approximate overlap geometry between the proflavine ring and nearest neighbor base pairs at the intercalation site from a comparison between experimental shifts and those calculated for various stacking orientations. We have compared the binding of actinomycin D, propidium diiodide, and proflavine to self-complementary tetranucleotide sequences dC-dC-dG-dG and dG-dG-dC-dC by UV absorbance changes in the drug bands between 400 and 500 nm. Actinomycin D exhibits a pronounced specificity for sequences with dG-dC sites (dG-dG-dC-dC), while propidium diiodide and proflavine exhibit a specificity for sequences with dC-dG sites (dC-dC-dG-dG). Actinomycin D binds more strongly than propidium diiodide and proflavine to dC-dG-dC-dG (contains dC-dG and dG-dC binding sites), indicative of the additional stabilization from hydrogen bonding and hydrophobic interactions between the pentapeptide lactone rings of actinomycin D and the base pair edges and sugar-phosphate backbone of the tetranucleotide duplex.


Structures of enzyme-substrate complexes of lysozyme.

Conformational energy calculations were used to determine the binding structures of two oligosaccharides (GlcNAc)(n), in which n = 5 and 6, in the rigid active site of lysozyme (mucopeptide N-acetylmuramoylhydrolase, EC 3.2.1.17). Starting with the lowest energy binding structures of (GlcNAc)(4) as determined in a previous publication, we added a fifth GlcNAc residue to this tetramer in three different conformations, corresponding to the left-handed and right-handed helical structures and an intermediate structure, and the energy of each complex was minimized. The most stable binding conformation of the fifth residue of the pentamer was closest to the left-handed helical one. During energy minimization, the fourth residue of the pentamer moved from its initial position near the surface of the active site farther into the active site cleft at binding site D. Binding structures of (GlcNAc)(6) were then examined by addition of a residue to the lowest energy structure of (GlcNAc)(5), and it was found that the sixth residue of the hexamer binds in a conformation again close to the left-handed helical one. Stable binding regions of the rigid active site for the fifth and sixth residues were found to be near arginyl 45 and asparaginyl 46, on the opposite side of the active site cleft from arginyl 114. When the calculated structure of the lysozyme-(GlcNAc)(4) complex (used here as the starting structure for addition of the fifth and sixth residues) is compared with recent experimental data, it is found that the calculated structure is a reasonable one. Of all binding regions available to the saccharide residues, the C site binds GlcNAc with the lowest energy, in agreement with experiments.


Ultraviolet resonant Raman spectroscopy of nucleic acid components.

The first resonant Raman excitation profile using UV as well as visible radiation is presented. Measurements of the intensity of the Raman spectrum of adenosine 5'-monophosphate as a function of the frequency of the incident laser light are presented in the range from 20 to 38 kK (1000 cm-1). The scattering intensity per molecule increases by about 10(5) as the laser is tuned from low to high frequencies. The Raman excitation profile has been calculated by using a simple form of the vibronic theory of Raman scattering. The theoretical curves are found to adequately fit the data using only the frequencies of the excited electronic states of AMP and their corresponding vibronic linewidths as adjustable parameters. The Raman bands at 1484 cm-1 and 1583 cm-1 appear to obtain virtually all of their intensity from a weak electronic transition at 276 nm. The set of Raman bands in the range 1300 cm-1-1400 cm-1 appear to derive at least part of their intensity from an electronic band whose 0-0 transition is in the 269-259 nm region although the possibility of some intensity arising from the vibronic mixing between these two electronic states cannot as yet be ruled out.


Molecular properties of the nerve growth factor secreted in mouse saliva.

Some molecular properties of the nerve growth factor (NGF) secreted in mouse saliva and that present in submandibular glands have been measured for comparison with previously studied forms of NGF. The results show that mouse saliva contains two biologically active NGF species. One has a molecular weight near 114,000, and the other, a molecular weight of 13,000. The larger form is being continuously degraded to yield the smaller one, probably as a result of a slow enzymatic process. Virtually identical results were obtained with crude submandibular gland extracts. The larger NGF is neither the well-known 7S NGF nor 2.5S NGF. Our results indicate that the larger salivary NGF is the naturally occurring form of NGF as it exists in the submandibular gland and as it is secreted in saliva. Its biological properties and its function in saliva, if any, remain to be elucidated.


Loss of infectivity of brome mosaic virus RNA after chemical modification of the 3' or 5' terminus.

Brome mosaic virus (BMV) RNA that had both termini chemically modified by periodate oxidation and aniline-catalyzed cleavage of the terminal nucleotide had drastically reduced infectivity. BMV RNA that was first enzymatically tyrosylated to protect the 3' terminus from modification, and then modified at the 5' terminus by periodate oxidation and aniline cleavage, had a similar reduction in infectivity. Tyrosylation followed by acetylation modifies only the 3' terminus. Nevertheless, acetylated tyrosyl-BMV RNA was less than one-fourth as infectious as a control sample subjected to procedures that differed only by the presence of tyrosinol (which prevents aminoacylation and subsequent acetylation). For each modified form of viral RNA, care was taken to test the infectivity of appropriate control samples. The integrity of the modified RNAs was examined by gel electrophoresis and by biological translation and aminoacylation assays. We conclude that, in different ways, both the 5'- and 3'-terminal structures of BMV RNA play important roles during infection of the host.


A site-specific single-strand endonuclease from the eukaryote Chlamydomonas.

We have found a unique deoxyribonuclease in extracts of the eukaryotic green alga Chlamydomonas. When incubated with viral DNA from adenovirus-2, this enzyme produces discrete fragments that form bands upon electrophoresis in an agarose gel. Site specificity of the enzymatic cleavage examined by identifying the 5'-terminal nucleotides in cleaved adenovirus-2 DNA and by studies with synthetic polynucleotides of defined sequence, indicates that the initial endonucleolytic cleavage occurs at a site containing a deoxythymidine residue. Electron microscopy of cleaved adenovirus-2 DNA revealed single-strand segments within duplex DNA. We propose that the enzyme acts by making initial site-specific single-strand incisions, followed by subsequent excision on the same strand, producing a gapped duplex molecule; and that double-strand scissions result from limited occurrence of overlapping single-strand gaps on complementary strands.


Biotinylinsulins as potential tools for receptor studies.

The preparation of affinity columns that contain insulin attached to Sepharose in a targeted manner by way of biotin-avidin noncovalent bonds is described. Insulin was acylated selectively at the amino terminus of the B chain with the N-hydroxysuccinimido ester of biotin to form N(alpha,B1)-biotinylinsulin. The ability of this modified insulin to stimulate rat epididymal adipocytes was (mean +/- SD) 94 +/- 9.6% (P, 0.05) that of the control insulin. N(alpha,B1)-Biotinylinsulin displaced 4-hydroxyazobenzene-2'-carboxylic acid from avidin, demonstrating affinity for this protein. The formation of the N(alpha,B1)-biotinylinsulin-avidin complex was visualized by cellulose acetate electrophoresis at pH 4. N(alpha,B1)-Biotinylinsulin combined with avidin attached to Sepharose to form affinity columns in which the hormone was attached to the support by strong noncovalent bonds. The determination of the loading of avidin-Sepharose columns with biotinylinsulin was greatly facilitated by the attached biotin which provided a marker whose concentration could be assessed accurately by titration with avidin. Biotinylinsulin attached to avidin-Sepharose beads retained the ability to stimulate rat epididymal adipocytes. The activity of several samples of these beads was about 15% that of free biotinylinsulin, based on the amount of biotinylinsulin anchored to the support. The advantages of biotinylated hormones for the targeted attachment of hormones to solid supports are discussed.


Interaction between the third complement protein and cell surface macromolecules.

The activated form of the third complement protein, C3b, forms a stable complex with components of plasma membranes and particulate entities such as zymosan. The complex resists the action of detergents and protein denaturants as well as extremes of temperature, salt concentration, and pH. It can, however, be broken by exposure to hydroxylamine or by ammonolysis followed by incubation with sodium dodecyl sulfate. Thus, the complex appears to result from a hydrophobic interaction as well as a bond susceptible to nucleophilic attack.


A DNA fragment containing the origin of replication of the Escherichia coli chromosome.

A 38 kilobase pair region of the Escherichia coli K12 chromosome containing the replication origin has been physically mapped with restriction endonucleases EcoRI and HindIII. Replication starts within or very near a 1.3 kilobase pair HindIII fragment in the middle of this region and proceeds outward in both directions with apparently equal speed. This pattern was observed in both dnaA and dnaC temperature-sensitive (ts) initiation mutants at the start of the synchronous round of replication which occurs after downshift from the nonpermissive to the permissive temperature.


Distribution of 5-methylcytosine in chromatin.

The content of 5-methylcytosine in eukaryotic DNA was measured by mass spectrometry. Almost equal amounts of methylated cytosine were found in the DNA of various tissues of the chicken. When chromatin or nuclei were digested with micrococcal nuclease, 50% of the DNA was found to be nuclease resistant. In contrast to this, over 75% of the 5-methylcytosine was protected from nuclease digestion by chromatin proteins. These results suggest that 5-methylcytosine is nonrandomly distributed with respect to the nucleoproteins.


Enzymes as reagents in peptide synthesis: enzyme-labile protection for carboxyl groups.

N-Benzyloxycarbonyl derivatives of isoglutamine and isoasparagine were coupled with arginine methyl ester through the action of dicyclohexylcarbodiimide. The resulting benzyloxycarbonyl derivatives of isoglutaminylarginine methyl ester and isoasparaginylarginine methyl ester were treated with trypsin for removal of the ester groups and then with porcine pancreatic carboxypeptidase B for liberation of arginine and the original benzyloxycarbonyl derivatives of isoglutamine and isoasparagine. This scheme represents a reversible masking of the side-chain carboxyl functions of aspartic and glutamic acid residues. Possible applications of esters and amides of arginine as reversible blocking groups in protein semi-synthesis are discussed along with prospects and strategies for developing related techniques of higher efficiency.


Glycophorin and the concanavalin A receptor of human erythrocytes: their receptor function in lipid bilayers.

Two integral glycoproteins from the human erythrocyte have been studied after their incorporation into lipid bilayer systems. Glycophorin (which is the M/N blood group determinant) and the concanavalin A receptor were isolated and purified prior to incorporation into model membranes by dialytic removal of detergent from lipid/protein solutions. Under the conditions described, glycoprotein receptors maintain their function in that they bind external agents specific for them, such as concanavalin A and immunoglobulins. So-called intramembranous particles are a feature of freeze-fractured preparations of lipid bilayers containing either (or both) glycoprotein(s), and to some extent each has a characteristic particle appearance. Liposomes containing the concanavalin A receptor (with or without glycophorin) are agglutinable by concanavalin A, whereas human erythrocytes are normally considered to be nonagglutinable by this lectin. Liposomes containing glycophorin alone are readily agglutinable by the appropriate glycophorin-directed M/N antiserum, as are human erythrocytes. The added presence of concanavalin A receptor in the liposomes can markedly inhibit agglutination by M/N antiserum without preventing immunoglobulin binding.


Superiority of interconvertible enzyme cascades in metabolic regulation: analysis of monocyclic systems.

A theoretical analysis of monocyclic cascade models shows that the steady-state fraction of covalently modified interconvertible enzyme is a function of 10 different cascade parameters. Because each parameter can be varied independently, or several can be varied simultaneously, by single or multiple allosteric interactions of ligands with one or more of the cascade enzymes, interconvertible enzymes are exquisitely designed for the rigorous control of key metabolic steps. Compared with other reglatory enzymes, they can respond to a greater number of allosteric stimuli, they exhibit greater flexibility in overall control patterns, and they can generate a greatly amplified response to primary allosteric interactions of effectors with the converter enzymes. Contrary to earlier views, the decomposition of ATP associated with cyclic coupling of the covalent modification and demodification reactions is not a futile process. ATP decomposition supplies the energy needed to maintain concentrations of modified enzyme at steady-state levels that are in excess of those obtainable at true thermodynamic equilibrium.


Concept of internal structural controls for evaluation of inactive synthetic peptide analogs: synthesis of [Orn13,14]apamin and its guanidination to an apamin derivative with full neurotoxic activity.

The importance of arginine residues 13 and 14 in the bee venom neurotoxin, apamin, was teste by the synthesis of replacement analogs. [13,14-di-Ndelta-trifluoroacetylornithine]Apamin was synthesized by the solid phase method on a benzhydrylamine resin. It was deprotected to [13,14-diornithine]apamin, which was then guanidinated to produce the 4-homoarginine-13,14-diarginine analog, [Har4]apamin. Neither the trifluoroacetylornithine analog nor the ornithine analog produced any detectable symptoms when injected intravenously into mice. However, the synthetic [Har4]apamin exhibited the full neurotoxic activity of native apamin and of [Har4]apamin derived from the natural toxin. This provided an internal structural control for the correctness of the primary structure of the inactive synthetic analogs and strengthened the conclusion that one, or both, of the arginine residues plays an important role in the action of apamin.


Discontinuous replication of replicative form DNA from bacteriophage phiX174.

Bacteriophage phiX174 DNA has been labeled with short pulses of [3H]thymidine during synthesis of replicative form molecules in infected Escherichia coli HF4704 cells. The replicating phiX174 DNA was isolated and analyzed by sedimentation in an alkaline sucrose gradient. During a brief pulse (5 sec at 30 degrees), the radioactivity incorporated into the complementary strand was found in chains much shorter than one genome length. Of the radioactivity incorporated into the viral strand, two-thirds was in the short pieces and the rest was in chains of one genome length or longer. RNA attachment to the 5' end of both strand components of the nascent short pieces was shown by the appearance of spleen exonuclease-digestable nascent molecules after alkali treatment. These observations suggest that the viral as well as the complementary strand is synthesized by the discontinuous mechanism with RNA primers during replication of duplex phiX174 DNA.


Nerve growth factor receptors: identification of distinct classes in plasma membranes and nuclei of embryonic dorsal root neurons.

Two classes of receptors for 125I-labeled nerve growth factor in chick embryonic dorsal root neurons have been observed. One type is associated with the plasma membrane (or microsomal fraction) and can be completely solubilized by Triton X-100. These receptors display the nonsaturable binding isotherms and curvilinear Scatchard plots previously reported for nerve growth factor receptors in whole cells. The second class of binding sites is located in the nucleus, firmly bound to chromatin. These receptors are not solubilized by detergent, show saturable binding, and yield linear Scatchard plots of the type associated with a single class of binding sites of high affinity. The presence of the two receptor types suggests a bimodal mechanism of action for nerve growth factor.


Isolation and identification of aliphatic short-chain acylcarnitines from beef heart: possible role for carnitine in branched-chain amino acid metabolism.

Aliphatic acylearnitines isolated from a water-soluble fraction of beef heart have been characterized by gas chromatography and mass spectrometry. The following acyl residues derived from the acylcarnitine fraction were unequivocally identified: acetyl, propionyl, isobutyryl, butyryl, alpha-methylbutyryl, valeryl, isovaleryl, tiglyl, and caproyl. beta-methylcrotonyl and methacrylyl were tentatively identified. This occurrence of considerable quantities of branched-chain acylcarnitines indicates a role for carnitine in branched-chain amino acid metabolism.


Molecular weight of bacteriorhodopsin solubilized in Triton X-100.

Bacteriorhodopsin from Halobacterium halobium has been solubilized in the nonionic detergent Triton X-100. The circular dichroic spectrum and hydrodynamic properties indicate that the structure of this protein in the detergent is not significantly altered from that of the native membrane-bound form. Bacteriorhodopsin is monomeric under the conditions of solubilization with a molecular weight of 24,250+/-2,000 and binds approximately one micelle of Triton X-100.


Selective association of the trout-specific H6 protein with chromatin regions susceptible to DNase I and DNase II: possible location of HMG-T in the spacer region between core nucleosomes.

Nuclei and chromatin from trout testis cells were digested with three different nucleases (DNase I, DNase II, and micrococcal nuclease), and the acid-soluble proteins that were solubilized and those remaining bound to the nuclease-resistant DNA were compared electrophoretically. With the conditions described by H. Weintraub and M Groudine [(1976) science, 193, 848-856], which we previously found to be selective in digesting actively transcribed regions in trout testis chromatin, a single chromosomal protein, H6, was solubilized. The nucleosomal histones and H1 remained insoluble, bound to the resistant DNA. In contrast, digestion with micrococcal nuclease led to a preferential solubilization of a second protein, HMG-T, together with the release of some nucleosomal histones and H1 into the soluble fraction. DNase II also discriminated between "active" and "inactive" chromatins; when a DNase II-solubilized "active" chromatin fraction was prepared, it too was enriched in H6 and HMG-T. Thus, both H6 and HMG-T, the two major low-salt extractable chromosomal nonhistone the two major low-salt extractable chromosomal nonhistone proteins from trout testis, are associated with chromatin regions selectively sensitive to nucleases. The preferential solubilization of HMG-T by micrococcal nuclease action suggests that it might be located at the internucleosomal "spacer" region.


DNA or RNA priming of bacteriophage G4 DNA synthesis by Escherichia coli dnaG protein.

Escherichia coli dnaG protein is involved in the initiation of DNA synthesis dependent on G4 or ST-1 single-stranded phage DNAs [Bouche, J.-P., Zechel, K & Kornberg, A. (1975) J. Biol. Chem. 250, 5995-6001]. The reaction occurs by the following mechanism: dnaG protein binds to specific sites on the DNA in a reaction requiring E. coli DNA binding protein. An oligonucleotide is synthesized in a reaction involving dnaG protein, DNA binding protein, and DNA. With G4 DNA this reaction requires ADP, dTTP (or UTP), and dGTP (or GTP). Elongation of the oligonucleotide can be catalyzed by DNA polymerase II or III in combination with dnaZ protein and DNA elongation factors I and III, presumably by the mechanism previously reported [Wickner, S. (1976) Proc. Natl. Acad. Sci. USA 73, 3511-3515] or by DNA polymerase I.


Structural convergence during protein evolution.

Several recent protein crystallographic structure determinations have demonstrated the existence of considerable tertiary structural similarity among proteins otherwise having little similarity in either amino acid sequence or biological function. In order to assess the possibility that such proteins may have arisen through processes of divergent evolution from a common ancestor, a graphical presentation is given which correlates the pattern of allowed single base substitutions defined by the genetic code with the associated changes in the structural properties of the encoded amino acids. The results show that while a large degree of structural conservation is evident due to codon synonomy, there is, in general, little tendency for the code to be structurally conservative in the majority of the cases where codon single-base changes result in amino acid substitutions. The possible consequences of this pattern of potential amino acid substitutions are discussed in relation to protein evolutionary processes.


Method for obtaining a high resolution protein map starting from a low resolution map.

A method is described for estimating the phases of high resolution single-crystal diffraction data from proteins, by using as a starting point a set of low resolution phases (about 3 A) derived by multiple isomorphous replacement (or other) methods. The method consists in refining by least-squares the positions and thermal parameters of a set of dummy atoms placed in the initial low resolution electron density map, so as to minimize the discrepancy between the calculated scattering intensities and the scattering intensities observed in the high resolution data set. Phases calculated from these refined atomic positions are used to extend the resolution and to improve the quality of the electron density map. The success of the method depends on a new least-squares algorithm that has a radius of convergence of about 0.75 A. This large radius of convergence, together with the severe restrictions placed on the initial positions of the dummy atoms by the requirement that they lie within limited regions of the isomorphous electron density map, and the constraint imposed by the polymeric nature of a polypeptide chain account for the success of the method. The method has been successfully used to phase the structure factors of 2-zinc insulin at a resolution of 2 A and 1.5 A, starting from a set of isomorphous phases at 3-A resolution.


The living state and cancer.

Complex living structures developed on our globe after the appearance of light and oxygen. In functions of these structures, solid state phenomena play a major role. The structural proteins were made into radicals by doping, the covalent incorporation of electron acceptors. This lent mobility to their electrons and a subtle reactivity to their molecules. Cancer is unable to go into the radical state.


Extensive disulfide bonding at the mammalian cell surface.

Cell surface proteins of cultured cells are disulfide bonded to a greater degree than are total cellular proteins. In particular, the "large external transformation-sensitive" (LETS) protein, a major surface protein, is present almost exclusively in disulfide-bonded complexes including homodimers and also higher aggregates held together by disulfide bonds or concovalent interactions. Other cell surface proteins also appear to be involved in disulfide bonding, both intramolecular and intermolecular. In virally transformed cells, LETS protein and its disulfide complexes are absent and certain other disulfide-bonded proteins are also not observed.


Effects of antitubulins on the redistribution of crosslinked receptors on the surface of fibroblasts and epithelial cells.

Substrate-attached normal mouse fibroblasts, transformed mouse fibroblasts (L strain), and epithelial cells (MPTR strain) were incubated with two ligands crosslinking different groups of the surface receptors: concanavalin A and cationic ferritin. Surface-attached ligands were revealed by an indirect immunofluorescence method. Incubation of control cells with these ligands induced the patching of corresponding surface receptors and the clearing of these receptors from the surface zones located on the lamellar cytoplasm near cell edges actively protruding pseudopodia. Effects of three antitubulins (microtubule-destroying drugs: Colcemid, colchicine, and vinblastine) on the ligand-induced redistribution of receptors were investigated and compared with the previously described effects of these drugs on the distribution of active cell edges. Incubation of normal and transformed fibroblasts with these antitubulins led to the disappearance of nonactive cell edges; the whole cell perimeter became active. Correspondingly, the clearing pattern of the surface receptors of fibroblasts was altered by antitubulins: the cleared area in antitubulin-treated cells formed a circular band along the whole peripheral cell edge. In epithelial cultures, in contrast to fibroblastic ones, antitubulins changed neither the distribution of the active sites of the surface nor the distribution of the areas cleared of crosslinked receptors. Thus, the specific ability of the surface areas located near the active cell edges to become cleared of crosslinked receptors is characteristic not only for the cells with intact microtubules, but also for the cells with microtubules destroyed with antitubulins.


Regulation of DNA synthesis: age-dependent cooperation among G1 cells upon fusion.

The object of this study was to determine whether the inducer(s) of DNA synthesis in mammalian cells accumulates gradually throughout the G1 period or becomes available suddenly at the G1-S transition. HeLa cells, synchronized at various points in the G1 period, were fused by using UV-inactivated Sendai virus. Early G1 cells were fused with mid-G1 or late G1 cells and late G1 cells were fused with mid-G1 cells. The G1 traverse of mono-, bi-, and trinucleated cells was studied. The bi- and trinucleated cells of mid-G1 and late G1 parents traversed the G1 period significantly faster than did their mononucleated counterparts. The reduction in the duration of the G1 period was proportional to the number and age of nuclei at the time of fusion. There was no significant difference between the mono- and binucleated cells of the early G1 parent in their rates of entry into S period. In light of these findings, a model is proposed in which the inducer(s) of DNA synthesis accumulates gradually throughout the G1 period, reaching a critical level at the G1-S boundary when DNA replication is initiated; after reaching a peak during early or mid-S period, it declines to below the critical level when DNA synthesis ceases.


Inhibition of cytokinesis in Friend leukemia cells by membrane mobility agents.

Treatment of a line of Friend leukemia cells with a dispersion of the membrane mobility agent, A2C, yields cells that undergo successive nuclear divisions without cytokinesis, resulting eventually in cells with as many as 30 nuclei. Neither the DNA replication rate of the cells nor the generation time is different after treatment; in addition, the multiple nuclei divide synchronously, and the chromosome number corresponds to the number of nuclei in the cell. Inhibition of cytokinesis is not observed if the cells are washed with reagent-free medium within 1 hr of treatment, but is observed if washing is delayed for 24 hr. Membrane mobility agent loaded with the fluorescent probe, Flomol F20C, leads to fluorescent membrane; fluorescence disappears from the membrane after a change of medium within 1 hr, but not after a change of medium within 24 hr. Some stages in the overall development resemble those seen for cytochalasin B inhibition of cytokinesis, although the mechanisms may well be different for the inhibition promoted by membrane mobility agent. The inhibition of cytokinesis by A2C provides a potentially interesting means of studying cytokinesis and the regulation of differentiation.


Tumor promoters inhibit spontaneous differentiation of Friend erythroleukemia cells in culture.

Clones of Friend erythroleukemia cells, characterized by the presence of 40-70% benzidine-positive cells synthesizing hemoglobin in the absence of inducing drugs, were treated with several phorbol diesters with a known range of tumor-promoting activity on mouse skin. Good correlation was found between the reported tumor-promoting activity of a particular phorbol diester and its ability to inhibit spontaneous erythroid differentiation in culture. The inhibition of differentiation by 12-O-tetradecanoyl-phorbol-13-acetate, the most active tumor promoter, was maximum after 4 days of treatment; this inhibition was reversed by removal of the phorbol diester no matter how long the period of treatment. Unlike control cells, which gradually revert to a population with a low percentage of benzidine-positive cells, cells treated with 12-O-tetradecanoyl-phorbol-13-acetate retained a high potential for spontaneous differentiation.


Independent expression of the adrenergic phenotype by neural crest cells in vitro.

Neural crest cells obtained from Japanese quail and grown in vitro without other embryonic tissues differentiate into adrenergic cells. These cells show intense catecholamine-specific histochemical fluorescence, and some have long, varicose neuronal processes. Ultrastructural examination shows two populations of cells, one with small (about 90 nm) dense-core vesicles resembling principal sympathetic neurons and the other with larger (about 150 nm) dense-core granules resembling chromaffin or small intensely fluorescent cells. Neuronal cells without adrenergic characteristics are also present. These results are compatible with the hypothesis that a population of cells determined along neuronal lines exists in the neural crest prior to migration.


Food, drug, and cosmetic dyes: biological effects related to lipid solubility.

Food, drug, and cosmetic dyes of the xanthane type (analogs of fluorescein) were applied to isolated molluscan ganglia and changes in the electrophysiological properties of identified neurons were monitored. The synthetic coloring agents increased the resting membrane potential and conductance of the neurons in a dose-dependent manner by increasing the potassium permeability of the membrane relative to that of other ions. The relative activity of these anionic dyes was highly correlated with their lipid solubility. The structure-activity study of the effects of the dyes on molluscan neurophysiology provides a basis for estimating the toxicity and brain uptake of the dyes in vertebrates, and predicting their effects on metabolism and blood clotting.


Hemoglobin F synthesis in vitro: evidence for control at the level of primitive erythroid stem cells.

The in vitro regulation of fetal hemoglobin (HbF was investigated in clones of cultured adult human erythroid cells by in situ immunofluorescent identification of the hemoglobins synthesized. Formation of Hb F-containing clones was enhanced by erythropoietin and by culture conditions favoring the proliferation of less-differentiated stem cells of the burst-forming-unit type. Burst-forming units differed in their capacity to direct Hb F synthesis in their terminally differentiated progeny. A class of early precursors that can produce descendent stem cells with or without commitment to Hb F production was identified. The findings suggest that the capability for expression of Hb F in terminally differentiated cells of the adult is determined at the level of less-differentiated erythroid stem cells with characteristics of burst-forming units. It is proposed that the regulation of Hb F synthesis in vivo is also linked to the process of differentiation of the erythroid stem cells and that the patterns of Hb F synthesis during ontogeny reflect the attainment of progressively higher levels of differentiation of erythroid stem cells as development proceeds.


Epigenetic variation of cultured somatic cells: evidence for gradual changes in the requirement for factors promoting cell division.

Cells of higher plant species in culture sometimes lose their requirement for an exogenous supply of a cell division factor that, thereafter, they are able to produce. This heritable change, known as cytokinin habituation, appears to be an epigenetic one rather than a classical mutation because it is directed, potentially reversible, leaves the cell totipotent, and involves the expression of a latent differentiated function. By using cloned cell lines derived from pith parenchyma of tobacco, we have obtained evidence that the habituation process is gradual rather than all-or-none and leads to progressively more autotrophic tissues. Cells in culture show reversible shifts among a range of habituated states but remain totipotent and can be induced to regain their requirement for a cell division factor. Thus, it appears that habituation involves epigenetic changes in a quantitative cellular phenotype. Our findings support the hypothesis that tumor progression in crown gall, a neoplastic disease of higher plants, can be accounted for by heritable changes in the pattern of gene expression.


Serial transfer of a human gene to rodent cells by sequential chromosome-mediated gene transfer.

The human hypoxanthine phosphoribosyl-transferase (IMP:pyrophosphate phosphoribosyltransferase, EC 2.4.2.8) gene (hprt) has been serially transferred to mouse cells and then to Chinese hamster fibroblasts by two cycles of metaphase chromosome isolation and incubation with recipient cells. Human metaphase chromosomes were incubated with mouse A9 cells deficient in hypoxanthine phosphoribosyltransferase, and independent colonies expressing the human species form of this gene were isolated in a selective medium. Metaphase chromosomes isolated from two of these clonal lines were incubated with Chinese hamster fibroblasts deficient in hypoxanthine phosphoribosyltransferase; five resulting independent colonies again expressed the human species of this gene. The transfer frequencies in the two cycles of chromosome-mediated gene transfer were similar (about 10(-7)). These results indicate that the transferred human chromosome fragment is closely associated with the chromosomes of the mouse A9 cells and it is probably integrated into the chromosomal DNA of the recipient cell.


Detection of active heteropolymeric beta-glucuronidase in hybrids between mouse cells and human fibroblasts with beta-glucuronidase deficiency.

Heteropolymeric beta-glucuronidases are detected in somatic cell hybrids between mouse cells and human fibroblasts deficient in beta-glucuronidase (beta-D-glucuronide glucuronosohydrolase, EC 3.2.1.31) by electrophoresis and column chromatography. Specific antisera against human beta-glucuronidase prepared in mice recognize these heteropolymeric beta-glucuronidases. Our results demonstrate that synthesis of mutant subunits of variant beta-glucuronidase continues in deficient human fibroblasts; these mutant subunits of human beta-glucuronidase retain the ability to associate with normal subunits of mouse beta-glucuronidase to form the enzymatically and immunologically active tetramer. These studies demonstrate the usefulness of interspecific cell hybrids for study of structural gene mutations of polymeric enzymes, such as those of beta-glucuronidase in mucopolysaccharidosis type VII.


Production of antibodies against influenza virus by somatic cell hybrids between mouse myeloma and primed spleen cells.

We have produced somatic cell hybrids between mouse myeloma cells and spleen cells derived from a BALB/c mouse immunized with purified influenza virus. The hybrid cells were found to produce large amounts of antibodies specific for the hemagglutinin of the virus and were able to induce tumor formation when injected into BALB/c mice.


Glycolipid-bound sialic acid in serum: increased levels in mice and humans bearing mammary carcinomas.

In mice bearing transplantable mammary carcinomas, serum levels of sialic acid-containing glycolipids were elevated 2.5-fold in pooled serum samples from which gangliosides were purified by column chromatography. A method is also described by which ganglioside content was estimated on as little as 1.0 ml of whole blood to permit studies with individual tumor-bearing mice and age- and litter-matched controls. Using this method, we observed similar elevations in ganglioside levels that were independent of age and sex of the animal and appeared in advance of palpable tumors. Following excision of the tumors, the glycolipid sialic acid values dropped below control levels and remained there. Serum sialic acid of the glycolipid fraction was elevated nearly 2-fold in human carcinoma patients and appeared to decline after surgery.


Isoantigenic expression of Forssman glycolipid in human gastric and colonic mucosa: its possible identity with "A-like antigen" in human cancer.

The heterogenetic Forssman antigen is a glycosphingolipid, a ceramide pentasaccharide with the structure GalNAcalpha1-->3GalNAcbeta1-->3Galalpha1-->4Galbeta1-->4Glc-->ceramide. Forssman-positive animals are capable of synthesizing this compound in tissues or in erythrocytes, in contrast to the Forssman-negative species, including humans, which are incapable of adding the last carbohydrate in the sequence of the Forssman antigen, namely alphaGalNAc. The Forssman glycolipid and its precursor globoside were examined in twenty-one samples of surgically extirpated gastrointestinal mucosa and tumors derived therefrom. The results revealed that a few patients had chemically and immunologically detectable levels of the Forssman glycolipid as a normal component of their gastrointestinal mucosa (F(+) population); in contrast, the majority of patients did not contain this glycolipid in their normal mucosa (F(-) population). Whereas the F(-) population included blood groups A, B, and O, the F(+) population did not correspond to blood group A. The Forssman status in tumors taken from the F(+) or F(-) population showed the following striking features: (i) all tumors derived from F(-) mucosa possessed Forssman glycolipid, whereas (ii) none of the tumors originating in F(+) mucosa contained Forssman glycolipid. Globoside, the immediate precursor of Forssman antigen, was distributed equally among F(+) and F(-) mucosa and the tumors derived therefrom. Thus, the expression of Forssman antigen in gastrointestinal mucosa appears akin to that of an isoantigen. Furthermore, the Forssman antigen that appears in tumors of the F(-) population could represent a human tumor-associated antigen. In view of the strong crossreactivity of Forssman antigen with blood group A determinants, the appearance of Forssman antigen in human tumors could be related to the "A-like antigen" (or "neo-A antigen") of human tumors reported previously [Hakomori, S., Koscielak, J., Black, K. J. & Jeanloz, R. W. (1967) J. Immunol. 98, 31-38; Häkkinen, I. (1970) J. Natl. Cancer Inst. 44, 1183-1193].


In vitro and in vivo correlation of clotting protease activity: effect of heparin.

The thrombogenicity of three highly purified proteases (thrombin, activated Factor X, and activated Factor IX) was determined quantitatively in an animal model. The minimal amounts required to produce a standard score 4 thrombus were 1.1 nmol for thrombin, 0.12 nmol for activated Factor X, and 0.018 nmol for activated Factor IX. After the administration of heparin at 5, 10, and 20 units/kg in rabbits, the thrombogenicity of each of these proteases decreased progressively. The heparin-induced inhibition of thrombosis decreased in the order, activated Factor IX > activated Factor X > thrombin at each heparin concentration. These differences were statistically significant. These in vivo data provide support for the following hypotheses originally developed from in vitro experiments: (i) activation of the blood coagulation system, which proceeds through a cascade mechanism, incorporates biochemical amplification; (ii) the inhibition of activated Factor IX by antithrombin III in the presence of heparin is an important reaction in the prevention of thrombosis; (iii) less heparin is required to inhibit thrombosis prior to thrombin generation than afterward; (iv) an increase in the reactivity of antithrombin III reflects a decreased tendency to thrombosis while a decrease in this reactivity reflects an increased tendency to thrombosis.


Cholecystokinin and its COOH-terminal octapeptide in the pig brain.

Two components--one resembling intact cholecystokinin in size and charge and immunologic specificity, and the other resembling the COOH-terminal octapeptide of cholecystokinin--have been found in extracts of the pig cerebral cortex. The relative concentrations of the two peptides in the extracts were dependent on the extractant, boiling 0.1 M HCl being more effective than boiling water for the extraction of intact cholecystokinin but less effective for the extraction of the octapeptide. The physiologic role of these peptides in the brain has yet to be elucidated.


Fatty liver induced in Zucker "fatty" (ff) rats by a semisynthetic diet rich in sucrose.

A new fatty liver model is described in which heredity plays a major role. A marked fatty liver develops when the homozygous mutant Zucker rat (ff or "fatty") is fed a semisynthetic diet enriched in sucrose. Lean littermates do not develop fatty liver on this experimental diet. Even old ff rats do not develop fatty livers on chow; the experimental diet is required. The fatty liver is described, including light microscopic and preliminary electron microscopic observations.


Measurement of daily cholesterol synthesis rates in man by assay of the fractional conversion of mevalonic acid to cholesterol.

A significant correlation has been found in man between total daily cholesterol synthesis rates as determined by sterol balance measurements and the fraction of intravenously administered R-[5-14C]mevalonic acid converted to cholesterol. In 30 studies it was found that the mean daily cholesterol synthesis rates estimated by sterol balance measurements ranged from 395 to 3047 mg/day, whereas the fractional conversion of mevalonate to cholesterol varied from 0.28 to 0.99. The two parameters correlated with a coefficient of 0.87, P less than 0.001. This method for estimating cholesterol synthesis rates requires low doses of radioisotopic materials (25 muCi of [14C]mevalonate and 5 muCi of [3H]cholesterol) and less than 1 hr of the patient's time; it can be repeated at intervals of 3 weeks and reflects cholesterol synthesis over a short period of time.


Authentic beta-globin mRNA sequences in homozygous betaO-thalassemia.

In a patient with homozygous betaO-thalassemia in whom studies of reticulocyte hemoglobin synthesis showed no beta-globin chain synthesis in vivo and in vitro, molecular hybridization studies revealed RNA sequences complementary to beta-globin cDNA. The fact that these sequences were authentic beta-globin mRNA was shown by fingerprint analysis of T1 ribonuclease-digested mRNA and by sequencing of oligonucleotides unique to beta-globin mRNA. The beta-mRNA that failed to direct beta-globin chain synthesis was not detectably shortened or degraded and contained poly(A) sequences.


Variation in ability of measles virus plaque progeny to induce interferon.

Plaque progeny of three interferon (IF)-inducing strains of measles virus (Edmonston, Schwarz, and CC) were examined for ability to induce IF in BSC-1 cells. Only after passage in Vero cells did any of the Edmonston progeny induce IF. The vast majority of plaque progeny selected from the Schwarz strain induced IF, even though this virus was originally derived from the Edmonston strain. This property was retained even after serial plaque purification of the progeny. However, the Schwarz-derived CC strain consisted of a population generally unable to induce IF. Stocks grown from both Edmonston and CC plaques demonstrating the IF+ phenotype maintained this characteristic as a whole, but it was not a property that was inherited by all progeny in the stocks. Levels of IF induced were approximately the same for all strains, even though the proportion of inducing progeny varied markedly among them. These noninducing variants appeared to be normal, fully infectious measles virions. The results suggest that induction of IF by measles virus is at least partially under the genetic control of the virus.


Nonlinear analysis of cat retinal ganglion cells in the frequency domain.

We have analyzed the responses of cat retinal ganglion cells to luminosity gratings that are modulated in time by a sum of sinusoids. A judicious choice of the component temporal frequencies permits a separation of the linear and second-order nonlinear components. Y cell responses show harmonic generation and intermodulation distortion over a wide frequency range. These nonlinear components predominate over the linear components for certain types of spatial stimuli. Nonlinear components in X cells are greatly diminished in comparison. The character of the nonlinear responses provides strong constraints on prospective models for the nonlinear pathway of the Y cell.


Modulation of acetylcholine receptor by antibody against the receptor.

Antibody against acetylcholine receptor induces an increase in the rate of degradation of acetylcholine receptors on a mouse cell line (BC(3)H-1) and cultured rat skeletal muscle. The increased rate of degradation results in a lowered density of acetylcholine receptors on muscle membrane and a lowered sensitivity to iontophoretically applied acetylcholine. The modulation of acetylcholine receptor is energy, temperature, and time dependent and may be related to antigenic modulation found in other systems. Acetylcholine noise analysis demonstrates that antibody against acetylcholine receptor reduces the channel mean conductance and mean open time slightly. It is concluded that antibody binds to the acetylcholine receptor, impairs its function, and induces receptor degradation. This results in a lowered density of acetylcholine receptor and a lowered sensitivity to acetylcholine. Patients with myasthenia gravis have antibodies to their acetylcholine receptor in their serum. Antigenic modulation of receptor in the muscle of patients with myasthenia gravis could contribute to the observed decrease in amplitudes of miniature endplate potentials and in muscle acetylcholine sensitivity, and the symptoms of muscular weakness.