Quantifying Distances Between Non-Elliptical Clusters to Enhance the Identification of Meaningful Emotional Reactivity Subtypes

Coordinated emotional responses across psychophysiological and subjective indices is a cornerstone of adaptive emotional functioning. Using clustering to identify cross-diagnostic subgroups with similar emotion response profiles may suggest novel underlying mechanisms and treatments.However, many psychophysiological measures are non-normal even in homogenous samples, and over-reliance on traditional elliptical clustering approaches may inhibit the identification of meaningful subgroups. Finite mixture models that allow for non-elliptical cluster distributions is an emerging methodological field that may overcome this hurdle. Furthermore, succinctly quantifying pairwise cluster separation could enhance the clinical utility of the clustering solutions. However, a comprehensive examination of distance measures in the context of elliptical and non-elliptical model-based clustering is needed to provide practical guidance on the computation, benefits, and disadvantages of existing measures. We summarize several measures that can quantify the multivariate distance between two clusters and suggest practical computational tools. Through a simulation study, we evaluate the measures across three scenarios that allow for clusters to differ in location, scale, skewness, and rotation. We then demonstrate our approaches using psychophysiological and subjective responses to emotional imagery captured through the Transdiagnostic Anxiety Study. Finally, we synthesize findings to provide guidance on how to use distance measures in clustering applications.

Modified Immunodiffusion Method for Detection of Salmonella in Raw Flesh and Highly Contaminated Foods: Collaborative Study

A total of 19 government and private industry laboratories in Canada and the United States participated in the collaborative study. Naturally contaminated ground poultry and animal meals, as well as inoculated raw shrimp, were examined for presence of Salmonella by both the modified immunodiffusion method and the Bacteriological Analytical Manual culture method, resulting in an agreement rate of 93.1%. The 2 methods are statistically equivalent for all food types at each inoculation level and for all lots of naturally contaminated foods evaluated in this study. The modification of the AOAC Official Method 989.13, immunodiffusion (1–2 TEST) method for detection of motile Salmonella in all foods, has been adopted revised first action by AOAC INTERNATIONAL.

Microsurgical resection of a glioblastoma multiforme of the medulla oblongata with intraoperative subcortical stimulation and mapping

Primary glioblastoma multiforme tumors of the medulla oblongata are rare, especially in the adult population. Perhaps due to this rarity, we are not aware of any previous reports addressing the resection of these tumors or their clinical outcomes.

In this surgical video, we present a 43-year-old man with a 1-month history of left-sided paresthesia. The paresthesia initiated in the left hand, along with weakness and reduced fine motor control, and then spread to the entire left side of the body. He had recent weight loss, imbalance, difficulty in swallowing, and hoarseness in his voice. He also had a diminished gag reflex, and significant atrophy of the right side of the tongue with an accompanying deviation of the uvula and fasciculations of the tongue. MRI showed an infiltrative expansile mass within the medulla with peripheral enhancement and central necrosis. In T2/FLAIR sequences, a hyperintense signal extended superiorly into the left inferior aspect of the pons and left inferior cerebellar peduncle and inferiorly into the upper cervical cord.

The decision was made to proceed with surgical resection. The patient underwent a midline suboccipital craniotomy with C1 laminectomy for surgical resection of this infiltrative expansile intrinsic mass in the medulla oblongata, with concurrent monitoring of motor and somatosensory evoked potentials and monitoring of lower cranial nerves IX, X, XI, and XII. A gross-total resection of the enhancing portion of the tumor was performed, along with a subtotal resection of the nonenhancing portion. The surgery and postoperative course were uneventful. Histopathology revealed a grade IV astrocytoma. The patient received radiation therapy.

In this surgical video, we demonstrate important steps for the microsurgical resection of this challenging glioblastoma multiforme of the medulla oblongata.

The video can be found here: https://youtu.be/QHbOVxdxbeU.

Mapping of the internal capsule with subcortical stimulation for gross-total resection of a thalamic metastatic tumor

Although the surgical treatment of thalamic tumors remains challenging due to the proximity to the internal capsule, safe resection of gliomas or metastatic tumors of the thalamus are possible in some selected cases due to a better understanding of microsurgical anatomy and due to advances in neurophysiological mapping and monitoring. In this video, the authors demonstrate the use of mapping of the internal capsule with direct subcortical stimulation for the resection of a metastatic tumor. The patient is a 58-year-old man with a history of renal cell carcinoma and metastasis in the left thalamus and parieto-occipital region. He underwent stereotactic radiation of both tumors at an outside hospital. Due to the increased size of both tumors and surrounding vasogenic edema, he was referred to the authors for resection. He underwent gross-total resection via an interhemispheric transcallosal approach. His postoperative course was uneventful and did not have any focal neurological deficits, including motor, sensory, or visual functions. The authors' surgical approach to this metastatic thalamic tumor and the intraoperative real-time direct subcortical stimulation of the internal capsule during surgery are demonstrated in this video. The video can be found here: https://youtu.be/DmDxjJUSZWU .

Management of the Maxillary Diastema by Various Dental Specialties

PURPOSE

There is considerable controversy in the literature concerning the indications for frenectomy for treating a maxillary diastema and for timing of the procedure. The purpose of this study was to survey pediatric dentists, orthodontists, and oral and maxillofacial surgeons on their opinion of this matter to develop a consensus.

MATERIALS AND METHODS

An anonymous 7-item electronic questionnaire was sent to members of the American Academy of Pediatric Dentists, the American Association of Orthodontists, and the American Association of Oral and Maxillofacial Surgeons asking about the etiology of the maxillary diastema, its diagnosis, and treatment.

RESULTS

Although there was no agreement among the oral and maxillofacial surgeons for the timing of frenectomy and when the diastema should be closed, the pediatric dentists and orthodontists generally agreed that frenectomy should not be performed before the permanent canines are erupted and that the operation should follow orthodontic closure of the space.

CONCLUSION

Although there was no complete consensus among the 3 groups, a logical treatment approach for the maxillary diastema is proposed.

Public and Patient Knowledge About Dental Implants

PURPOSE

The more informed a patient is about a given procedure, the better the ultimate outcome. This study was designed to compare general public awareness and knowledge regarding oral implant treatment with those of patients presenting for such treatment and to determine the sources from which they may have obtained such information, as well as the accuracy of the information.

PATIENTS AND METHODS

In this cross-sectional study, 2 groups of patients were asked to complete a questionnaire containing implant knowledge questions and questions regarding any sources they may have used to obtain information about dental implants. Group I consisted of patients presenting for treatment of a dental emergency (general population group), and group II consisted of patients presenting for an implant consultation. The χ² test was used to determine whether there were differences in knowledge and information sources between the 2 groups.

RESULTS

A total of 126 adult patients (76 dental emergency patients and 50 implant consultation patients) participated in the study. The general population group was less informed about dental implants, especially information relating to implant material and longevity, and received information from less reliable sources than patients presenting for implant screening (friends or relatives vs primary dentist). Both groups reported cost of the procedure as a primary barrier to receiving implants (89% and 90%).

CONCLUSIONS

There is still a need for continued education of the general public regarding dental implants.

Canine oral fibrosarcomas: a retrospective analysis of 65 cases (1998-2010)

The objective of this retrospective study was to report the outcome of treatment of canine oral fibrosarcomas (FSA) in relation to median survival and progression-free survival (PFS), and to report whether grade was prognostic in relation to median survival. Sixty-five dogs with oral FSA presented to the WSU VTH between June 1998 and March 2010. Significant predictors of median survival were location (P = 0.0099), tumour size or oral stage (P = 0.0312), type of surgery (P = 0.0182), margins (P = 0.0329) and grade (P = 0.0251). Significant predictors of PFS were location (P = 0.0177), and radiation protocol (P = 0.0343). A combination of surgery and radiation was the strongest predictor of prolonged median survival (P = 0.0183) and PFS (P = 0.0263) at 505 and 301 days, respectively. Treatment of canine oral FSA with a combination of surgery and radiation therapy provided the longest median survivals.

Three cases of congenital adrenal hypoplasia with novel mutations in the (NROB1) DAX-1 gene

Abnormalities in the DAX-1 gene (dosage-sensitive sex reversal-adrenal hypoplasia gene on the X chromosome) are a well-recognized cause of congenital adrenal hypoplasia. DAX-1 is expressed in the adrenal cortex, gonads, hypothalamus and anterior pituitary, which gives rise to the clinical features of this deletion. Presentations are varied but salt-wasting and/or hypoglycaemia are the most common in an infant, with late onset of hypogonadotrophic hypogonadism. Over 80 different mutations in this gene have been identified. We present three unrelated cases with variable clinical presentations, all with novel mutations in the DAX-1 gene.

Congruence of tail use behaviors between male and female mantled howling monkeys (Alouatta palliata)

//8RDifferences between males and females in locomotor and positional behaviors have been documented for several primate species [1, 2]. In Alouatta palliata for example, females climb and use smaller substrates more than males [3–5]. Such sex differences are usually related to body size. Indeed, interspecific studies have repeatedly demonstrated relationships between body size and locomotor and positional behaviors. It is easier, for example, for a large primate to suspend beneath a branch than to balance on top of it [6, 7]. This is particularly true for primates that feed near the periphery of the crown, where branches tend to be smaller.

Australian military trauma management: experiences in Rwanda and Papua New Guinea

The military trauma management experiences in the 1950s and 1960s were some of the catalysts for the development of emergency medical services systems worldwide. How is the Australian military managing trauma in light of the recent experiences in Rwanda and Papua New Guinea?

An international validation of the interaction with disabled persons scale

The Interaction with Disabled Persons Scale (IDP) was devised to measure attitudes in terms of discomfort reported about social interaction with people with disabilities. The Scale has been used in Australia for ten years. This article reports results of an international validation project that was designed to determine whether psychometric characteristics and norms emerging for Australian groups apply elsewhere. A methodological proforma was developed to maximize uniformity of data collection across nine countries: Australia, Canada, Croatia, England, Germany, Hong Kong, Poland, Scotland and the United States. In most countries the Scale was administered in English; however it also was translated into Germany, Polish, French and Croat. Results indicate that across countries mean scores fell within ten points, similar moderate to high levels of item homogeneity occurred and level of prior contact with people with disabilities emerged as the strongest predictor of IDP scores. It was concluded that the IDP Scale is a valid measure that is able to discriminate between respondents within the countries included in the study.

A controlled trial of immunotherapy for asthma in allergic children

BACKGROUND

Injections of allergens are widely prescribed for patients with asthma, but little is known about the effectiveness of immunotherapy.

METHODS

We conducted a double-blind, placebo-controlled trial of multiple-allergen immunotherapy in 121 allergic children with moderate-to-severe, perennial asthma. The children, who required daily medication for their asthma, were randomly assigned to receive subcutaneous injections of either a mixture of up to seven aeroallergen extracts or a placebo. Maintenance injections were continued for 18 months or longer. Medications were adjusted every two to three weeks on the basis of peak flow rates and symptoms. The principal outcome was the daily medication score. Bronchial sensitivity to methacholine (the concentration provoking a 20 percent decrease in the forced expiratory volume in one second [PC20]) was measured twice yearly.

RESULTS

The median medication score declined from 5.4 to 4.9 in the immunotherapy group (P<0.001) and from 5.2 to 5.0 in the placebo group (P<0.001), but there was no significant difference between the groups (P>0.6). The number of days on which oral corticosteroids were used was similar in the two groups. Partial or complete remission of asthma occurred in 31 percent of the immunotherapy group and in 28 percent of the placebo group (P>0.5). There was no difference between the groups in the use of medical care, symptoms, or peak flow rates. The median PC20 increased significantly in both groups, but again with no difference between the two groups.

CONCLUSIONS

Immunotherapy with injections of allergens for over two years was of no discernible benefit in allergic children with perennial asthma who were receiving appropriate medical treatment.

The role of the pediatric nurse practitioner in educating teens with mental retardation about sex

Adolescents with mental retardation have sexual needs that are often overlooked, underestimated, or considered problematic by parents, teachers, or other caregivers. This article describes ways in which the pediatric nurse practitioner can help these special teens develop responsible social and sexual relationships through assessment, education, coordination of services, appropriate referrals, and regular follow-up.

The efficacy of a semirigid ankle stabilizer to reduce acute ankle injuries in basketball. A randomized clinical study at West Point

This randomized clinical study was designed to prospectively determine the efficacy of a semirigid ankle stabilizer in reducing the frequency and severity of acute ankle injuries in basketball. Athletic shoe, playing surface, athlete-exposure, ankle injury history, and brace assignment were either statistically or experimentally controlled. Participants in the study were 1601 United States Military Academy cadets with no preparticipation, clinical, functional, or radiographic evidence of ankle instability. Subjects experienced a total of 13,430 athlete-exposures in the 1990 and 1991 intramural basketball seasons. Ankle injury was defined as acute trauma to the ankle ligaments that resulted in an athlete's inability to participate in basketball 1 day after the injury. Use of ankle stabilizers significantly reduced the frequency of ankle injuries. Reduction in ankle injuries, however, depended on the nature of injury (fewer contact injuries occurred among those who wore braces). Injury severity was not statistically reduced, and wearing the ankle stabilizer did not affect the frequency of knee injuries. Attitude toward ankle stabilizer use improved as use of the stabilizer increased.

Carboplatin (CBDCA) plus alpha interferon in metastatic non-small cell lung cancer. A Hoosier Oncology Group phase II trial

Interferons have been shown to increase in vitro cytotoxicity of platinum compounds. The Hoosier Oncology Group has conducted a Phase II clinical trial to determine if interferon alpha-2a (IFN-alpha-2a) given in combination with carboplatin (CBDCA) can increase response rates or survival in patients with metastatic or recurrent inoperable non-small-cell lung cancer. Forty-four patients with no prior chemotherapy and high KPS (80-100) were enrolled. CBDCA 400 mg/m2 was given intravenously on day 1 and IFN-alpha-2a 9 million units was given subcutaneously on days 1, 3, and 5. Treatment was administered every 4 weeks until onset of progressive disease or to a maximum of 4 courses: 37 patients (84%) received at least 2 courses, whereas only 16 (36%) received the full 4 courses. Dose-limiting toxicities were leukopenia (27%) and thrombocytopenia (20%) attributable to CBDCA. Grade 2-3 anemia occurred in 32%. Only 4-7% of patients experienced severe fever, fatigue, or flu-like symptoms attributable to interferon administration. Of 41 patients evaluable for response, there were no complete responses and only 3 (7.3%) partial remissions. The overall median survival was 6 months. The combination of CBDCA and IFN-alpha-2a given in this dose and schedule does not appear to have superior activity compared to CBDCA alone in patients with non-small-cell lung cancer.

Clinical experience with penicillin skin testing in a large inner-city STD clinic

OBJECTIVE

To establish (1) the prevalence of positive penicillin skin tests among outpatients with well-defined but variable history of penicillin allergy and (2) the reproducibility, safety, and negative predictive value of skin testing with benzylpenicilloyl polylysine (PPL) and a minor-determinant mixture (MDM).

DESIGN

Serial consenting outpatients with current indications for penicillin therapy were skin-tested in duplicate with PPL and MDM. Subjects with negative skin tests (93% of those positive by history and 95% of those negative by history) received therapeutic courses of benzylpenicillin (81%) or ampicillin (19%). Negative predictive value of skin testing was established by 72-hour follow-up for adverse reactions to drug.

SETTING/PATIENTS

A total of 5063 consecutive, qualifying outpatients in a Baltimore, Md, sexually transmitted disease (STD) clinic. The study group was young (73% between 20 and 40 years old), 66% male, and 90% black; 25% had history of atopy. Follow-up was 94% complete.

RESULTS

Positive skin tests were observed in 7.1% of 776 individuals with previous history of penicillin allergy and in 1.7% of 4287 subjects negative by history (P << .001). Previous history of anaphylaxis or urticaria was associated with significantly higher rates of positive skin tests of 17.3% and 12.4%, respectively (P<<.001). Only 4% with history of exanthem had positive skin tests (P = .03). The coefficient of variation for duplicate skin tests was 11%. Time intervals since last penicillin treatment did not influence the rate of positive skin tests. Adverse reactions to skin tests occurred in 13 (1.2% of patients positive by history; 9.4% of those with positive skin tests). A mild anaphylactic reaction occurred in one individual whose preliminary scratch testing was inadvertently omitted; systemic pruritus or urticaria occurred in 11 subjects; one had a large local reaction. After penicillin administration to individuals with negative skin tests, acute allergic reactions occurred in 0.5% of subjects negative by history compared with 2.9% of subjects positive by history (chi 2 = 33.3; P = .0001). Reactions were generally mild and self-limited; only two cases of mild anaphylactic reaction occurred, both in patients with history of severe IgE-mediated reaction.

CONCLUSIONS

Skin testing with both major and minor penicillin determinants is safe using current recommendations, and both reagents are necessary for maximizing the identification of sensitized subjects. Routine penicillin skin testing can facilitate the safe use of penicillin in 90% of individuals with a previous history of penicillin allergy.

Phase III trial of cyclophosphamide versus cyclophosphamide, doxorubicin, and methotrexate in hormone-refractory prostatic cancer. A Hoosier Oncology Group study

BACKGROUND

Between August 1984 and November 1989, the Hoosier Oncology Group conducted a Phase III study comparing cyclophosphamide (CTX) with cyclophosphamide, doxorubicin, and methotrexate (CAM) in patients with hormone-refractory metastatic prostatic cancer to determine whether the addition of doxorubicin and methotrexate to the cyclophosphamide regimen conferred any survival advantage.

METHODS

One hundred three patients were registered and randomized, 99 were evaluable for response, and all were evaluable for survival results. All had histologically confirmed metastatic prostatic cancer and had not responded to hormonal therapy. Fifty-three patients received CTX alone, and 50 received CAM. Seventy-one patients (69%) had evaluable disease, and 32 (31%) had measurable disease.

RESULTS

There were no complete responses and only four (13%) partial responses in the patients with measurable disease. There was no difference in overall survival time between the two treatment arms in either patients with a Karnofsky performance status (KPS) of 80-100 (median survival, 9.0 versus 9.5 months; P = 0.93) or in those with a KPS of 50-70 (median survival, 5.0 versus 6.0 months; P = 0.51). There was no difference in overall time to progression between the two treatment arms (median time to progression; 4.4 versus 6.2 months; P = 0.07). Toxicity was tolerable in both regimens.

CONCLUSIONS

It was concluded that there was no survival advantage to CAM over CTX alone. New chemotherapeutic agents with greater activity against prostatic cancer must be identified.

Effect of chlorhexidine scrub on postoperative bacterial counts

Chlorhexidine surgical scrub was left on the surgeon's hands in 50 orthopedic and vascular surgical procedures to determine whether the number of bacteria on the hands could be decreased postoperatively. After a standard 5-minute scrub, one hand was randomly rinsed prior to gloving; the other was lightly patted with a sterile towel, leaving some foam on the hand. The surgeon then gloved and performed the procedure in the usual manner. After the operation, both hands were immersed in a tryptic soy broth for 30 seconds. The broth was then cultured for bacterial species and number. Cases in which glove puncture occurred were not cultured. The results were analyzed using the Wilcoxon signed-rank test. There were fewer bacterial colonies isolated from the hand coated with chlorhexidine scrub versus the other; this difference was statistically significant (p less than 0.005). There also seemed to be a trend towards higher bacterial counts after longer operations; however, the difference was not significant. Neither surgeon noted any evidence of dermatitis during the study. These results suggest that leaving chlorhexidine scrub on the hands during surgery can lead to lower bacterial counts on the surgeon's hands and less chance of wound contamination should glove puncture occur.

A protocol for performing reproducible methacholine inhalation tests in children with moderate to severe asthma

Reproducibility of methacholine inhalation tests (MIT) over a 2-wk period has been established in adult populations, but similar studies demonstrating reproducibility in children are lacking. We set out to establish the reproducibility of MIT in children as a prerequisite for a study of the natural history of airway hyperreactivity in asthmatic children. Most inhalation testing is done in persons with mild asthma because the recommended time interval for the withholding of medications prior to bronchial challenge is poorly tolerated by more labile asthmatics. In order to evaluate asthmatics with more severe disease, we modified a standardized method of methacholine inhalation to include a three-tier pretest medication regimen and investigated the reproducibility of this MIT protocol in 11 children as young as 6 yr of age. The three tiers were designed to keep baseline FEV1 greater than or equal to 70% predicted since diminished baseline airway caliber may affect MIT results. Eight of the 11 children were bronchodilator-dependent, and two of the eight also required inhaled steroids. Eleven children (6 to 13 yr of age) underwent MIT, between December and March, 1 day, 1 wk, and 1 month after an initial test. The PD20FEV1 using cumulative breath units (BU) were compared. The range of PD20FEV1 in the 11 children was 0.27 to 14.4 BU, with nine subjects classified as severe (PD20FEV1 less than 2.5 BU). We found a high degree of reproducibility of MIT. The interest correlation coefficient (r) was 0.98 after 1 day, 0.95 after 1 wk, and 0.96 after 1 month.(ABSTRACT TRUNCATED AT 250 WORDS)

Antigenic analysis of household dust samples

Household dust samples from the homes of 106 allergy clinic patients in Baltimore were analyzed for specific allergen content. Dust mite antigen content was determined by enzyme-linked immunosorbent assays (ELISA) specific for the major allergens of Dermatophagoides pteronyssinus, D. farinae, and D. microceras. Cat and dog antigen content were determined by ELISA using antisera for Fel d 1 (formerly cat allergen 1) and dog allergens 3 and 13, respectively. Mold content was assessed by culture with microscopic identification. Dust mite antigen was detected in 99% of homes (D. farinae, 95%; D. pteronyssinus, 88%; D. microceras, 31%), with total antigen content ranging from 50 ng/g dust (the lower limit of detection) to 30,170 ng/g (median, 1,123 ng/g). Animal allergens were found in 100% of samples (cat: range, 2 to 130,000 ng Fel d 1/g; median, 90 ng/g; dog: range, 112.5 to 585,000 IU/g; median, 2,719.5 IU/g). Although there were highly significant differences in antigen content (p less than 0.001) between homes with and without a particular pet in residence, many homes without pets contained pet allergens at high concentrations. Molds were also detected in 100% of homes (range, 4 to 761 colonies/30 mg dust; median, 72 colonies/30 mg). No correlation was demonstrated between antigen content and skin test results, a history of asthma, symptoms on allergen exposure, or the age of the home (except for molds) for any of the allergens detected. We conclude that dust mite allergens, cat and dog allergens, and molds are virtually ubiquitous in Baltimore homes and that our ability to predict the presence and relative quantities of these allergens on clinical grounds is very limited.

Merkel cell carcinoma (endocrine carcinoma of the skin) of the head and neck

Merkel cell carcinoma, also known as endocrine carcinoma of the skin, is a recently recognized and particularly aggressive form of skin cancer that exhibits histologic features similar to those of endocrine malignant neoplasms arising from other tissues. Forty-one patients with Merkel cell carcinoma arising from the cutaneous surfaces of the head and neck were seen at the University of Texas M. D. Anderson Hospital, Houston, between 1966 and 1983. Regional lymph node metastasis occur early and frequently, with a 79% overall incidence observed during the course of the disease. Treatment should consist of a wide resection of the primary tumor. A regional lymphadenectomy, when feasible, is successful in controlling nodal metastases. Postoperative radiation is recommended as an important adjuvant.

Pyomyositis. Report of 18 cases in Hawaii

Eighteen patients with pyomyositis were seen at a large hospital in Hawaii. Most were healthy young men or boys, and eight had never traveled abroad. Fever, muscle pain and swelling, and leukocytosis were common, but only seven had erythema or fluctuance. A single large muscle was infected in 14, and two to three muscles were infected in the others. Pyomyositis mimicked cellulitis, muscle hematoma, thrombophlebitis, appendicitis, and neoplasm. Staphylococcus aureus was found in 13, and Streptococcus pyogenes was found in two. Bacteremia occurred in 29% (5/17). Drainage and antimicrobial agents were usually effective therapy, but one patient died and another had CNS damage. The pathogenesis is uncertain, but 12 had nonpenetrating muscle injury and 13 had pyoderma, suggesting that bacteria invade injured muscle via the bloodstream or lymphatic system.

Lack of cross-reactivity between aztreonam , a monobactam antibiotic, and penicillin in penicillin-allergic subjects

Monobactam antibiotics are a new class of beta-lactam antibiotics. In contrast to penicillins or cephalosporins, monobactams possess a monocyclic beta-lactam structure. IgE or immediate hypersensitivity cross-reactivity between aztreonam (a monobactam) and penicillin was investigated, since this will be an important consideration when therapy is chosen. The maximum concentration of aztreonam reagents not giving false-positive skin tests was determined in normal subjects who were not allergic to penicillin. Subsequently, 41 subjects with IgE antibody to one or more penicillin moieties, as determined by positive skin reactions, were tested with the aztreonam reagents. Thirty-seven of these persons showed no reactivity while four showed equivocal tests. Repeat tests in those four persons were negative to the aztreonam reagents, while their penicillin tests remained unchanged. These in vivo data suggest that there is no cross-reactivity between IgE antibodies to penicillin and aztreonam and provide a basis for investigating the therapeutic use of monobactams in patients who are allergic to penicillin.

Quantitative description of cell cycle kinetics under chemotherapy utilizing flow cytometry

A discrete time cell cycle kinetics model is developed to account for the effects of cytotoxic chemotherapy, particularly including the existence of cells destined to die. A model structure is determined from related experiments, leaving key parameter values undetermined. These values are found by determining the best least squares fit of the predicted to the observed DNA distribution data at a series of time intervals. The numerical methods include separable least squares, linear inequality constrained least squares and the Gauss--Newton method. This approach is applied to an experiment in which the Ehrlich ascites tumour was given a single dose of bleomycin. The results include several different parameters, including the age response function and a time series of cell age and DNA distributions, which can be used as a basis for further treatment.

The release of alkaline phosphatase and of lipopolysaccharide during the growth of rough and smooth strains of Salmonella typhimurium

A rough strain of Salmonella typhimurium, which has a defect in the "inner core" region of its lipopolysaccharide, was shown to release more alkaline phosphatase into the medium during growth than did an isogenic smooth strain of the same organism. The pattern of enzyme release varied during growth in that early logarithmic phase cells retained alkaline phosphatase in their periplasmic space and at their cell surface while cells in later growth phases shed as much as 6% of their content of this enzyme into the medium. The reaction product localization technique used in this study enables us to assess enzyme production and localization in individual cells of a culture. The release of the enzyme was paralleled by a release of lipopolysaccharide from the cells. The released alkaline phosphatase shows a strong tendency to associate with purified phenol-extracted lipopolysaccharide.

The surgical separation of the thoracopagus conjoined twins of Korat, Thailand

Images

A radioisotopic method for determining optimum non-surgical therapy for advanced cancer. II. Clinical experience

Images