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Biomedical subjects

G Logan

Publications and source records attributed to G Logan.

17 recordsLinked to original sources
PubMed2001

The mandibular canal of the edentulous jaw.

The morphology of the mandibular canal after loss of teeth has received little detailed attention. Improved documentation of this topic would allow better interpretation of dental radiographs and would enable those engaged in tooth implantation to better understand the nature of the tissue into which the prostheses are placed. In this study on mandibles from seven dissecting room cadavers panoramic radiographs usually showed the mandibular canal clearly, an incisive canal less so. The wall of the mandibular canal was similar in dentate and edentulous mandibles, and was highly perforated, as suggested by Cryer (Anderson et al., 1991). In edentulous specimens, it was composed mainly of cancellous bone with only occasional single osteons. The inferior alveolar nerve near the mandibular foramen was a large trunk, consisting of three to four nerve bundles with connective tissue sheaths. It became more loosely arranged toward the mental foramen. Medial to the mental foramen, the nerves were frequently in the form of small bundles in the marrow. Any incisive canal was ill-defined and neurovascular bundles, when present, ran through a labyrinth of intertrabecular spaces.

Aged↗
PubMed2000

A practical approach to evidence grading.

BACKGROUND: The Institute for Clinical Systems Improvement (ICSI) is a collaboration of 17 Minnesota medical groups. Among other activities, ICSI develops health care guidelines and technology assessment reports. To maintain focus on the underlying evidence, ICSI has developed an evidence and conclusion grading system for use by the practicing clinicians who write the documents and use them in making decisions about patient care. THE EVIDENCE GRADING SYSTEM IN DETAIL: The centerpiece of the evidence grading system is the conclusion grading worksheet, which calls for statement of a conclusion, summarization of research reports that support or dispute the conclusion, assignment of classes and quality markers to the research reports, and assignment of a grade to the conclusion. EXPERIENCE AND RESULTS: The system has been used in the writing of more than 40 guidelines and numerous technology assessment reports. An example of a worksheet from the congestive heart failure guideline is presented. The system has helped the drafting groups to attend to the evidence. The methods have proven to be well accepted by practicing physicians and to be practical, although staff expertise in epidemiology is needed to support the system. Grading of conclusions appears to be reliable, although this characteristic of the system has not been rigorously tested. The outputs are valued by users of the documents. DISCUSSION: Although some residual problems remain to be solved, the system appears to be successful in overcoming the complexity of some published systems for grading evidence while still yielding a defensible classification of conclusions based on the strength of the underlying evidence.

Academies and Institutes↗
PubMed2000

Modality differences in short-term memory for rhythms.

Prior research has established that performance in short-term memory tasks using auditory rhythmic stimuli is frequently superior to that in tasks using visual stimuli. In five experiments, the reasons for this were explored further. In a same-different task, pairs of brief rhythms were presented in which each rhythm was visual or auditory, resulting in two same-modality conditions and two cross-modality conditions. Three different rates of presentation were used. The results supported the temporal advantage of the auditory modality in short-term memory, which was quite robust at the quickest presentation rates. This advantage tended to decay as the presentation rate was slowed down, consistent with the view that, with time, the temporal patterns were being recoded into a more generic form.

Adult↗
PubMed1998

Identification of a dynamic intracellular reservoir of CD86 protein in peripheral blood monocytes that is not associated with the Golgi complex.

In the process of developing a cancer immunotherapy strategy, we have identified and characterized a novel intracellular reservoir of CD86 protein in peripheral blood monocytes. This observation emerged from studies aimed at using retrovirus vectors to genetically modify tumor cells to express the costimulatory proteins CD80 and CD86. Retrovirus-mediated expression of CD80 and CD86 in T lymphoblastoid CEM cells resulted in an unexpected intracellular focal concentration of both proteins in the genetically modified cells. By extending these studies to an analysis of CD80 and CD86 expression in PBMC, we observed that endogenous CD86 expression in peripheral blood monocytes also involved a similar intracellular focal concentration of the protein. The intracellular concentration of CD86 in monocytes was not due to storage within the Golgi apparatus, and required intact microtubules to retain structural integrity. Furthermore, as the intensity of CD86 fluorescence increased on monocytes as a function of time in vitro, the intracellular focal concentration correspondingly decreased. These results are consistent with antegrade CD86 transport from an intracellular reservoir to the cell surface membrane. In this report, we detail the intracellular and membrane localization studies with tumor cell lines and PBMC, and describe the temporal relationship between intracellular storage and trafficking of CD86 to the cell surface membrane in peripheral blood monocytes. We hypothesize that this intracellular reservoir allows rapid and sustained deployment of an important costimulatory molecule to the monocyte surface membrane during initiation and maturation of the cell-mediated immune response.

Antigens, CD↗
PubMed1995

Methylphenidate and cognitive flexibility: dissociated dose effects in hyperactive children.

A randomized, double-blind, placebo-controlled trial was conducted to assess the acute effects of placebo and three doses of methylphenidate (MPH) (0.3, 0.6, 0.9 mg/kg) on cognitive flexibility and overt behavior in 28 children with a confirmed diagnosis of attention deficit-hyperactivity disorder. Two underlying cognitive processes (response inhibition and response reengagement) were assessed by measuring the probability and speed with which subjects could inhibit responses to a primary task (forced-choice letter discrimination) and immediately execute a response to a secondary task (simple reaction time) when given a signal to do so. Results indicated that MPH enhanced cognitive flexibility, although the high dose was less effective than lower doses in enhancing response inhibition. Dissociations of dose effects on cognitive function and behavior were demonstrated: Dose-response functions for changes in behavior were linear, whereas the function for response inhibition was U-shaped. Findings argue against the typical clinical practice of determining the response to stimulant treatment from a single measure such as parent report of child behavior.

Arousal↗
PubMed1995

Deficient inhibitory control in attention deficit hyperactivity disorder.

The purpose of this study was to examine two executive control processes--response inhibition and re-engagement of responses after inhibition in children with attention deficit hyperactivity disorder (ADHD). Thirty-three children with ADHD and 22 normal control children of similar age (7 to 11 years) and mean IQ (107) were tested with the change paradigm. ADHD subgroups were defined by the context in which the ADHD symptoms predominated (in the home only; at school only; and in both, i.e., pervasive ADHD). Children with marked oppositional defiant or conduct disorder were excluded. Children with ADHD exhibited deficits in inhibitory control and in response re-engagement. Deficits were greatest in pervasive ADHD and, to a lesser extent, in those with ADHD limited to the school context. ADHD limited to the home context showed the least deficit. These results replicate an earlier study that found deficient inhibitory control in pervasive ADHD and demonstrate that the deficit in ADHD involves a second aspect of executive control.

Attention Deficit Disorder with Hyperactivity↗
PubMed1991

Circulating tumor necrosis factor, interleukin-1 and interleukin-6 concentrations in chronic alcoholic patients.

Although altered cytokine homeostasis has been implicated in the pathogenesis of alcoholic liver disease, the relationship between cytokines and metabolic consequences of alcoholic liver disease is unknown. We, therefore, sought to correlate circulating concentrations of tumor necrosis factor-alpha, interleukin-1 and interleukin-6 to clinical and biochemical parameters of liver disease in chronic alcoholic patients. We used an enzyme-linked immunosorbent assay to measure plasma tumor necrosis factor and interleukin-1 and a bioassay to measure serum interleukin-6 in three groups of alcoholic men as follows: (a) actively drinking alcoholic men without evidence of chronic liver disease, (b) nondrinking alcoholic men with stable cirrhosis and (c) patients with acute alcoholic hepatitis. Mean cytokine concentrations were elevated in cirrhotic patients and alcoholic hepatitis patients compared with controls and alcoholic patients without liver disease. Tumor necrosis factor-alpha and interleukin-1 alpha concentrations remained elevated for up to 6 mo after diagnosis of alcoholic hepatitis, whereas interleukin-6 normalized in parallel with clinical recovery. Concentrations of all three cytokines were correlated with biochemical parameters of liver injury and hepatic protein synthesis plus serum immunoglobulin concentrations. We could not demonstrate a relationship between cytokine concentrations and peripheral endotoxemia. Percentages of peripheral blood monocytes that reacted with monoclonal antibodies to CD25 (interleukin-2 receptor) and human lymphocyte antigen-DR were similar for alcoholic patients and controls. These data suggest that tumor necrosis factor-alpha and interleukin-1 alpha are related to some of the metabolic consequences of both acute and chronic alcohol-induced liver disease, whereas interleukin-6 is related to abnormalities seen in acute liver injury.

Adult↗
PubMed1990

Are hyperactive children deficient in attentional capacity?

A dual task was used to study attentional capacity in three groups: in 6- to 12-year-old boys with attention deficit disorder plus hyperactivity (ADDH) or with ADDH and conduct disorder, and in normal children. Subjects performed a primary-choice reaction-time task first without and then with a secondary task that also required a response. Our prediction that the reaction time of ADDH subjects to the secondary task would increase more with increasing temporal overlap of the primary and secondary stimuli, if they were deficient in capacity, was not supported. However, the performance of ADDH subjects on the primary task deteriorated more than that of control subjects with the introduction of the secondary task, indicating a greater concurrence cost or a different allocation policy. Moreover, ADDH subjects had longer reaction times to the secondary task, indicating greater refractory effects or difficulty shifting capacity from primary- to secondary-task processes.

Attention↗
PubMed1989

Effects of event rate and display time on sustained attention in hyperactive, normal, and control children.

Two experiments were conducted to determine whether hyperactive boys have a unique deficit in sustained attention. Groups with DSM-III diagnoses of attention deficit disorder (ADDH), conduct disorder (CD), ADDH + CD, and learning disorder were compared with normal controls on the Continuous Performance Task. In Experiment 1, stimulus presentation rate (stimulus onset asynchrony, SOA) and display time were varied to manipulate attentional demand, and speed and accuracy of performance were measured. The ADDH group was uniquely affected, with less accurate performance at the fastest and slowest SOA. To distinguish the effects of time on task and SOA, the duration of each SOA condition was held constant in Experiment 2. The poorer performance of the ADDH group at the fastest SOA was no longer evident. This finding indicates that the deficit of sustained attention in boys who have ADDH is associated with a greater susceptibility to refractory effects, which is influenced by practice.

Arousal↗
PubMed1988

Attaining and maintaining preparation: a comparison of attention in hyperactive, normal, and disturbed control children.

The hypothesis that hyperactive children have a deficit in sustained attention was investigated. Eighteen children who had attention deficit disorder with hyperactivity (ADDH), aged 7 to 11 years, were compared with children who had conduct disorder (n = 15), mixed conduct disorder and ADDH (n = 26), emotional disorder (n = 18), or learning disability (n = 22), and with normal controls (n = 15). The subjects were tested on three versions of the Continuous Performance Task. Sustained attention was assessed from performance with increasing time on task and from ability to prepare attention in response to a warning. Performance of all subjects deteriorated with increasing time and improved with the opportunity to prepare attention. Hyperactive subjects were not more adversely affected by increasing time, nor did they benefit less than controls from the opportunity to prepare attention. Data reanalysis after rediagnosis according to ICD-9 criteria did not change the results. This study did not confirm the hypothesis that hyperactive children have a unique sustained attention deficit.

Affective Symptoms↗
PubMed1988

Prospective study of lower respiratory tract infections in an extended-care nursing home program: potential role of oral ciprofloxacin.

PURPOSE: Infections of the lower respiratory tract pose an important problem in nursing homes. Despite the magnitude of this problem, few, if any, antibiotic studies have been targeted specifically at nursing home-acquired bronchopulmonary infections. Following the establishment of a teaching Extended-Care Nursing Home Program, which facilitated the early diagnosis and therapy of bronchopulmonary infections, a comparative trial of oral ciprofloxacin and intramuscular cefamandole was initiated in elderly patients with lower respiratory tract infections. In addition to assessing the relative efficacy and safety of ciprofloxacin and cefamandole, our goals were to identify problems and pitfalls associated with conducting clinical research in this nursing home setting, evaluate selected clinical and laboratory features of lower respiratory tract infection in this patient population, and measure outcomes in all study groups. PATIENTS AND METHODS: During a 20-month period, 40 patients with pneumonia and 20 patients with acute bronchitis were enrolled in this randomized study. Sixty-three patients with pneumonia who were ineligible for the randomized study were also followed prospectively. The mean age of the 111 participants (123 cases) was 80.8 years; all patients had at least one chronic medical condition. RESULTS: Although Streptococcus pneumoniae was the single most common isolate, gram-negative bacteria were cultured from 81 percent of the cases that yielded pathogens from a satisfactory sputum specimen. The in-hospital mortality rate was strikingly low (6.5 percent), and a large majority of patients in all study groups were discharged safely back to their nursing homes well within the Diagnosis-Related Group length of stay. CONCLUSION: Ciprofloxacin appeared to be as safe and effective as cefamandole in this nursing home program; however, additional studies are needed to determine its role in the treatment of elderly patients with bronchopulmonary infections.

Administration, Oral↗
PubMed1976

Successful interposition synthetic graft between aorta and right coronary artery. Angiographic follow-up to sixteen months.

A knitted Dacron filamentous vascular prosthesis, 4 cm. long and 3.5 mm. in diameter, was used as an interposition graft between the aorta and right coronary artery in a 65-year-old woman on Oct. 25, 1974. The prosthesis was used to transplant the right coronary artery incident to removal of a saccular aneurysm if the ascending aorta. Concomitant mitral valve replacement and tricuspid annuloplaty were performed. The graft was demonstrated patent by angiograms 2 weeks, 7 months, and 16 months after the operation, and the patient continues to be clinically well 17 months postoperatively. The literature records the successful use of aorta-coronary Dacron prostheses in 2 other patents, both children with coronary anomalies. One of these grafts closed after a while: the second was demonstrated patent by angiograms 8 years after implantation. These cases demonstrate that prostheses can function in the aorta-coronary position, and the reports of saphenous vein failures indicate the need for a reasonable substitute when a patient's saphenous veins are absent or inadequate. In all 3 cases, the prostheses were quite short and were used as interposition grafts between the ascending aorta and the proximal end of the coronary artery. Our review did not reveal successful use of a synthetic graft for aorta-coronary bypass.

Aged↗
PubMedDate not supplied

Sexuality concerns of the post-stroke patient.

Sexuality concerns of the post-stroke patient often are overlooked in the clinical setting during rehabilitation and post-discharge care. Research has indicated that patients welcome frank and open discussion of the topic, although it seldom occurs. Research findings also indicate that changes in sexuality after a stroke often are due to changes in role function because of the increased dependency of the afflicted partner. This article discusses the research related to sexuality in the post-stroke patient, as well as indicators of sexual dysfunction in this population. Research findings are related to nursing care. Specific patient examples are given, along with suggestions for incorporating assessment of sexuality concerns into nursing care of the post-stroke patient.

Adult↗