Analysis of the radiobiology of ytterbium-169 and iodine-125 permanent brachytherapy implants

Recently, Yb-169 has been considered as a potential replacement for I-125 and Pd-103 in permanent implants. In spite of the uncertainties in the parameters necessary for an accurate radiobiological modelling, the linear quadratic model can be useful in the comparative evaluation of the radiotherapeutic merit of similar implants. In order to find out if a Yb-169 permanent implant can be made biologically 'equivalent' to an I-125 implant, we studied the dependence of local control on the tumour cell radiosensitivity and on the balance between the rate of tumour cell killing and tumour cell proliferation, for rapidly and slowly proliferating tumours. The extrapolated response dose (ERD) has been calculated for tumour and late reacting normal tissue for both types of implants and the possible biological restrictions due to the normal tissue tolerance have been discussed. Our theoretical analysis is consistent with the clinical results published for I-125 permanent implants in prostate tumours and meningiomas. It predicts that Yb-169, which has only recently been used in human tumours, can provide comparable tumour control for permanent implants in slowly proliferating tumours with an initial dose rate of 13 cGy h-1. Control might be extended to rapidly proliferating tumours by increasing the initial dose rate within a range consistent with an acceptable level of normal tissue late reaction.     

Bronchial atresia and bronchogenic cyst in an adult

We present the case of an asymptomatic patient, with a right paracardiac mass discovered in a preoperative radiologic study. The bronchoscopy showed the intermedius bronchus atresia, finished in bottom of sack, with absence of middle and lower right lobes. With the chest computed tomographic scan, two lobulated contour mediastinal masses were seen. The patient was submitted to surgery, being the pathological findings consistent with bronchogenic cysts with atresia of the intermediarius bronchus. The patient evolved favourably after surgery.     

Hispanics and worksite health promotion: review of the past, demands for the future

During the last 15 years, reports, books, and published papers have demonstrated the positive health benefits of comprehensive health promotion and disease prevention interventions at the worksite. Although the progress made in worksite health promotion should not be understated, experts agree that it is time to step forward and address the new demands of the changing labor force. One area of intervention that needs to be more aggressively addressed is that of minority populations. Because work force projections show the high participation rate that Hispanics will have in the future labor force, the Hispanic population should be one of the targets of worksite health promotion. This paper reviews how employee health promotion programs have addressed Hispanic workers in the past and establishes directions for the future.     

Alpha-L-fucose: a potentially critical molecule in pathologic processes including neoplasia

Alpha-L-fucose is a 6-carbon deoxyhexose that is commonly incorporated into human glycoproteins and glycolipids. It is found at the terminal or preterminal positions of many cell-surface oligosaccharide ligands that mediate cell-recognition and adhesion-signaling pathways. These include such normal events as early embryologic development and blood group recognition and pathologic processes including inflammation, infectious disease recognition, and neoplastic progression. Fucosylated oligosaccharide ligands mediate cell-cell adhesion through binding to cell-surface selectins (calcium-dependent binding proteins) and calcium-dependent interactions with other cell-surface carbohydrate counterligands. A number of fucose-containing "natural ligands" are common to inflammatory and malignant cell processes. We review evidence that alpha-L-fucose is critically important for cell-cell and cell-matrix adhesion in a variety of normal and pathologic processes, particularly neoplasia. Current results suggest that alpha-L-fucose provides the essential structure that enables carbohydrate ligands to bind to selectins and to carbohydrate counterligands and thereby alter cellular homeostasis.     

Interactions between non-immune host cells and the immune system during periodontal disease: role of the gingival keratinocyte

OBJECTIVE: The role of sympathetic blocks in pain therapy is examined in the light of changing concepts of pain pathophysiology. A critical review of the literature also sought to develop an evidence-based analysis of outcome studies to provide recommendations for appropriate applications of sympathetic blocks, together with ideas for further clinically based research. METHODS: A focus on the pathophysiology of neuropathic and inflammatory pain disorders was used to help redefine what contribution, if any, was provided by the sympathetic system, to chronic pain states. Validation of nerve block therapies based on historical practices and these newer concepts and outcome determinations has then been used to present an overview of clinical nerve block therapies as applied to the sympathetic nervous system. RESULTS: 1. Pain Diagnosis: A reclassification of reflex sympathetic dystrophy (RSD) to the new taxonomy of complex regional pain syndromes (CRPS) is supported, with evidence that only a questionable sympathetic contribution at the dorsal root ganglion level can be ascribed etiologically to this group of disorders. Sympathetic blocks can establish whether pains may be nonresponsive or variably responsive to such blocks, but are considered inappropriate in determining a clinical diagnosis. 2. Neuropathic Pain Therapy: (a) A critical review of the literature regarding the use of sympathetic blocks in the treatment of acute herpes zoster pain and in the treatment of postherpetic neuralgia found little support for the widely held view that sympathetic blocks reduced either the incidence of long-term reduction of pain in these disorders. Further attempts to reduce PHN by the combination of blocks with aggressive drug therapies during acute herpes infection are suggested. (b) CRPS (RSD) treatments are seen as evolutionary at present, with the role of sympathetic blocks being only part of a balanced pain treatment strategy aimed at getting patients activated under cover of good analgesia and improved function. These proposals come as consensus recommendations but are not substantiated by outcome studies. 3. Ischemic Pain: Permanent sympathetic block with neurolytic or thermocoagulation techniques provides up to 50% long-term improved blood flow and reduction of pain and ulceration for patients with advanced peripheral vascular disease. This is particularly appropriate at lumbar levels in which percutaneous techniques are safe when conducted with real time imaging control. CONCLUSIONS: Changes in the understanding of CRPS disorders and the role of the sympathetic nervous system in neuropathic pain has changed both the diagnostic and management strategies for these pain states. The sensitivity and specificity of response to sympathetic blocks in establishing their value at diagnostic aids will not be fully established without further clinical study. Further use of intravenous regional blocks or diagnostic intravenous infusions remains questionable. Preventive and therapeutic use of sympathetic blocks in herpes zoster pain remains open to well-controlled study.     

Differences in self reported morbidity by educational level: a comparison of 11 western European countries

Raman and infrared spectra were examined for guanosine 5'-diphosphate (GDP) and guanosine 5'-triphosphate (GTP) in aqueous solution. The vibrational modes were assigned on the basis of isotopic frequency shifts and relative intensities in the Raman and infrared spectra. The observed frequency shifts on 18O isotope labeling made it possible to identify the bands from each phosphate group (alpha, beta, gamma). Frequency shifts were observed as Mg2+ complexes with GDP and GTP. The results suggested that Mg2+ binds to GDP in a bidentate manner to the alpha, beta P[symbol: see text]O bonds and in a tridentate manner to the alpha, beta and gamma P[symbol: see text]O bonds of Mg.GTP. The results indicate that structure of Mg2+ coordinated to GTP in aqueous solution differs somewhat to that found for Mg.ATP.     

Replication and integration of a Vibrio cholerae cryptic plasmid linked to the CTX prophage

We identified a 4.7kb cryptic plasmid in all ctxAB+ Vibrio cholerae strains we tested. An isolate of the V. cholerae classical biotype strain 0395 that harbours the cryptic plasmid at high copy number was found. Hybridization analysis demonstrated that sequences highly related or identical to this plasmid exist in all toxigenic strains of V. cholerae but were notably absent in all non-toxigenic environmental isolates that lacked the genes for toxin-co-regulated pili and the filamentous CTX prophage. Accordingly, we have named the cryptic plasmid pTLC for toxin-linked cryptic. The complete nucleotide sequence of pTLC from the high-copy-number isolate was determined. The largest open reading frame in the plasmid is predicted to encode a protein similar to the replication initiation protein (pII) of Escherichia coli F-specific filamentous phages. The nucleotide sequence of pTLC also facilitated the structural characterization of the DNA homologous to pTLC in other strains of V. cholerae. pTLC-related DNA exists in these strains as both low-copy-number, covalently closed circular DNA and tandemly duplicated, chromosomally integrated DNA. Remarkably, the chromosomally integrated form of pTLC is adjacent to the CTX prophage. The strain distribution, chromosomal location and DNA sequence of pTLC suggests that it may be a genetic element that plays some role in the biology of CTXphi, perhaps facilitating either its acquisition or its replication.     

Nonoperative management of secondary shoulder impingement syndrome

Shoulder pain secondary to impingement of the rotator cuff tendons underneath the coracoacromial arch is a common problem seen in athletes who perform repetitive overhead activities. Shoulder impingement has been classified into primary and secondary types. Several factors contribute to impingement, including rotator cuff weakness, posterior capsule tightness, and subacromial crowding. Recently, it has been proposed that scapulothoracic muscle weakness could be a factor that contributes to impingement. Traditional rehabilitation protocols for shoulder impingement syndrome stress individualized rotator cuff strengthening. The authors propose that individualized scapulothoracic muscle strengthening should be a part of any protocol for nonoperative treatment of secondary shoulder impingement syndrome.     

Cerebral edema in acute hepatic failure: clinicopathologic correlation

A child developed acute fulminant viral hepatitis and cerebral edema confirmed on postmortem examination. Clinical evidence of herniation, effacement of cortical sulci on computed tomography, and elevated cerebrospinal fluid pressure preceded complicating terminal events, demonstrated that cerebral edema was associated with acute hepatic failure, rather than complicating factors, and led to the patient's death. The mechanism is unknown.