Scaling Laws for Branching Vessels of Human Cerebral Cortex

Objective: Vascular architecture, particularly of cerebral microvessels, has profound implications for both health and disease in a variety of areas, such as neuroimaging, angiogenesis and development, Alzheimer's disease, and vascular tumors. We analyzed the architecture of tree‐like vessels of the human cerebral cortex. Methods: Digital three‐dimensional images of the microvascular network were obtained from thick sections of India ink–injected human brain by confocal laser microscopy covering a large zone of secondary cortex. A novel segmentation method was used to extract the skeleton and measure the diameter at every vertex. Results: In this paper, we focus on the topology of the cortical tree‐like vessels. Using stem‐crown decomposition, power‐scaling laws were shown to govern the relationships between integrated parameters, such as the distal cumulative length, volume, or normalized flow. This led us toward an experimental confirmation of the allometric equation between mass and metabolic rate. Inversely, the power‐law model did not match the relationships between local parameters, such as diameter, and integrated ones. As a consequence, Murray's law did not appropriately model the architecture of cerebrovascular bifurcations. Conclusions: This study provides a unique, large database and mathematical characterization that may prove valuable for modeling the cerebral.     

Building and mobilizing partnerships for health: a national strategy

Increasingly, health professionals are being called upon tobe knowledgeable about and to integrate prevention and healthpromotion into their day-to-day practice. Working in partnershipwith a variety of disciplines and sectors is also an emergingreality in the health field. This paper describes a nationalcollaborative strategy development process ‘EnhancingPreventive Practices of Health Professionals’ that involvedHealth and Welfare Canada and eight national health professionalassociations. The lessons learned from the process and the documentsproduced by the initiative are highlighted. Reference is madeto related literature from the fields of organizational andcommunity development.     

Improved Dual Chamber Pacing Mode in Paroxysmal Atrioventricular Conduction Disorders

GIRODO, S., ET AL.: Improved Dual Chamber Pacing Mode in Paroxysmal Atrioventricular Conduction Disorders. Dual chamber pacing may sometimes be directly indicated for carotid sinus hypersensitivity, vasovagal syndrome, and certain cases of sinoatrial block and intermittent atrioventricular (AV) block, although AV conduction is dominantly normal. At times of normal AV conduction, competition between ventricular pacing and spontaneous ventricular depolarization may occur, with its adverse hemodynamic effects on ventricular function and unnecessary drainage of pacemaker battery energy. A new mode of stimulation is described, called automatic DDD mode, which functions in 'pseudo-AAI' mode during normal AV conduction and reverts to classical DDD function during episodes of AV blocks. Furthermore, during pseudo-AAI function, the pacemaker measures certain physiological parameters that serve to automatically program certain parameters used in DDD mode. Preliminary clinical evaluation has shown that this new mode functions satisfactorily.     

Expression of the 67 kD laminin receptor in human cervical preneoplastic and neoplastic squamous epithelial lesions: an immunohistochemical study

Interactions of cancer cells with laminin play a critical role during the progression of solid malignant tumours. Increased expression of the 67 kD laminin receptor (67LR), one of the several laminin binding proteins, is associated with the invasive and metastatic capacity of various types of cancer, including breast, colon, ovary, lung, and endometrial carcinoma. In this study, 67LR expression was analysed in a series of cervical biopsy specimens including 16 normal cervical tissues, 36 low-grade squamous intraepithelial lesions (SILs), 24 high-grade SILs, and 11 invasive carcinomas. Detection of the 67LR was performed using immunoperoxidase staining and the monoclonal antibody MLuC5 which specifically recognizes the 67LR. Immunostaining of the 67LR was correlated with human papillomavirus (HPV) type detected by in situ hybridization and with proliferative activity of the lesion determined by immunohistochemistry with the MIB-1 monoclonal antibody, specific for the Ki67 antigen. Increased expression of the 67LR was correlated with the histological severity of the lesions, with the strongest immunoreactivity being found in invasive carcinomas. Significant differences in 67LR expression were found between normal cervical epithelium and high-grade SILs (P<0·05, non-parametric Mann-Whitney test) or invasive carcinomas (P<0·001), as well as between low- or high-grade SILs and invasive carcinoma (P<0·01 and P<0·05, respectively). Ki67 antigen expression also increased with the severity of the lesions. There was a positive correlation for each type of lesion between expression of the 67LR and of the Ki67 antigen. No specific relationship was found between 67LR or Ki67 antigen immunostaining and HPV type detected in SILs, segregated into low-grade and high-grade lesions. These data add weight to the evidence that increased expression of the 67LR is a consistent, but not sufficient feature of the invasive and metastatic phenotype and suggest that high expression of the 67LR might be associated with both more proliferative and more aggressive cervical (pre)neoplastic lesions. © 1997 John Wiley & Sons, Ltd.     

Comparison of 55% TFA/CH2Cl2 and 100% TFA for Boc group removal during solid-phase peptide synthesis

Two parallel syntheses of 40 C-terminal amide peptides, ranging in length from 4 to 20 residues, have been carried out using simultaneous multiple peptide synthesis. All synthetic steps, other than the removal of the Boc group, were performed simultaneously under identical experimental conditions. The two sets of peptides were deprotected with either 55% TFA/DCM for 30 min or 100% TFA for 5 min. The purity of the peptides obtained when deprotecting with 55% TFA/DCM was, on average, 9% higher than with 100% TFA. The major impurity obtained during synthesis when 100% TFA was used for Boc removal corresponded to the omission of the second amino-acid residue added. Volumetric measurements of the swelling of the resin in the different deprotection solvents were carried out. These showed that the omission analogs generated are probably due to insufficient swelling of the resin, resulting in limited solvent transfer of 100% TFA into the resin and, in turn, incomplete Boc removal.     

Latex allergy in children: modalities and prevention

Allergic or immediate hypersensitivity reactions to latex have been reported in children with increasing frequency in the past. The reported prevalence varies greatly depending upon the population studied and the methods used to detect sensitization. Children's subpopulations at particular risk include: atopics, individuals with spina bifida, children undergoing surgical procedure during the neonatal period and individuals who required frequent surgical instrumentations. Latex allergy is also an important medical issue, particularly for healthcare personnel. Sensitization mainly occurs by wound or mucosal contact with latex devices during surgery or by inhalation of airborne allergens released from powdered latex gloves. Regarding diagnosis, the medical history, skin prick test and search for specific serum IgE are crucial but cost effective. The development of a guide listing latex-containing drugs is essential for the primary prevention of allergic reactions. Immunotherapy or specific premedication seems not effective in preventing the risk of anaphylaxis during the perioperative course. The most effective strategy to decrease the incidence of latex sensitization is complete avoidance. This strategy is efficient in patients and also in health care workers and has been applied since 2002 in our pediatric surgical hospital. One of major problem with the latex-free gloves was that surgeons find them considerably more difficult to work with. But today, manufacturers made considerable effort and free-latex gloves with an equal tactile sensation than the latex-gloves are now available. The extra cost of free latex gloves is well counterbalanced as allergen test, long stay hospital for allergic reaction, and worker's compensation are no longer needed. Since the introduction of this program in our institution, no allergic reaction to latex has been reported in 25000 anesthetized children or with the health care workers.     

Agminated Spitz Nevi Arising on a Nevus Spilus after Chemotherapy

Abstract: Agminated Spitz nevus arising on a background of nevus spilus (NS) is a rare condition. We report here a further case in a child that is original because it is induced by chemotherapy. A 3‐year‐old boy presented 3 months after the onset of a chemotherapy for a vesico‐prostatic rhabdomyosarcoma, multiple pigmented papulo‐nodules located on the face, neck, chest wall, and the higher back. These lesions have arose on a pre‐existent large congenital histologically confirmed nevus spilus extending along the face, neck, the left shoulder and the left chest wall. Histological examination of three excised nodules led to the diagnosis of Spitz nevus. Our patient may have a high risk for melanoma since he has many criteria predisposing to this risk. Some of these criteria are related to NS but we should also take into account the chemotherapy induction and the high number of Spitz nevi.     

Severe hyponatraemia after plastic surgery in a girl with cleft palate, medial facial hypoplasia and growth retardation

A ten-year-old girl with middle face hypoplasia, cleft lip and palate developed severe hyponatraemia on the first day following surgery. Final diagnosis was inappropriate secretion of antidiuretic hormone (ADH) and complete hormonal investigation revealed partial deficit in growth hormone secretion. The incidence of hormonal deficiency associated to midline facial malformations is discussed.