Endovascular interventions training and credentialing for vascular surgeons

This article reviews issues concerning the training and credentialing of vascular surgeons in the use of endovascular techniques in the peripheral vascular system. These guidelines update a prior document that was published in 1993. They have been rewritten to accommodate the rapid evolution that has occurred in the field and to provide the appropriate requirements that a vascular surgeon should fulfill to be competent in the basic skills needed to safely and effectively perform all presently accepted diagnostic and therapeutic endovascular procedures.     

Assessing neuromuscular block at the larynx: the effect of change in resting cuff pressure and a comparison with video imaging in anesthetized humans

Neuromuscular block (NMB) at the larynx has been assessed by measuring the cuff pressure (CP) in an endotracheal tube (ETT) placed between the vocal cords. In this study, we evaluated the decrease in resting cuff pressure (RCP) after the administration of rocuronium and the effect of this decrease on the assessment of NMB, and we compared CP measurement with an alternative technique, video imaging (VI). In 20 patients, NMB was determined at the hand by mechanomyography and at the larynx initially by CP and subsequently by VI, recording images using a fiberoptic bronchoscope via a laryngeal mask. Train-of-four stimuli were applied at both sites. After baseline measurements, the ETT was replaced, and rocuronium was infused to achieve a steady-state 50% (n = 10) or 75% (n = 10) block at the hand. CP measurements were recorded before and after restoration of RCP to prerocuronium pressure, followed by further VI measurements. The mean RCP decreased from 21 +/- 4 to 12 +/- 5 mm Hg after rocuronium. At 50% block at the hand, the CP estimate of block at the larynx with reduced RCP was 62% +/- 18%, and that after restoring RCP was 29% +/- 13%; VI estimated 27% +/- 14% block. At 75% block at the hand, CP and VI estimated 52% +/- 11% and 46% +/- 9% block, respectively (RCP maintained). We conclude that RCP decreases after the administration of rocuronium, that restoring RCP significantly alters CP estimates of NMB, and that VI is in agreement with CP measurement if RCP is maintained at prerelaxant values. Implications: In this study, we show that a muscle relaxant-induced decrease in resting tension at the larynx may confound the assessment of neuromuscular block by cuff pressure measurement. The preliminary data suggest that video imaging may provide a suitable alternative to cuff pressure measurement to assess neuromuscular block at the larynx.     

Physiological variation and adaptability in human populations

This review traces some of the developments in population physiology based on contributions to the Annals over the last 25 years. Two broad themes are evident, physiological systems variation and adaptation, and by way of introduction an historical perspective of their relationship within human ecology is explored. Studies of physical fitness and work capacity, and the efforts to create standardized field procedures make up a number of the early papers. Longitudinal studies have provided reliable reference standards for Westernized populations, but are virtually non-existent for primitive groups. The relative importance of phenotypic and genotypic variations in working capacity have yet to be clearly defined. The level of habitual activity during childhood contributes to the development of ventilatory capacity though constitutional influences are of major importance. Variability in strength and motor performance of skeletal muscles are shown to have a direct bearing on aspects of growth, development and biological maturation. Physical and psychological stress in communities have been investigated. These and other studies contribute valuable data on the issue of stress, hypertension and cardiovascular morbidity and mortality. On the theme of human adaptability, high altitude populations, variations in thermal tolerance and adaptations in ageing populations have all received recent investigation. Highland people of all ages have considerably larger lung volumes than coastal dwellers. Haematological, biochemical and pulmonary function show adaptive phenomena that vary in different highland groups. In the tropical biome, more recent work includes the functional consequences of malnutrition, ethnic and cultural differences in work capacity, and the effects of endemic disease on physical performance. Annals of Human Biology papers have more recently contributed to investigations on morphological and physiological changes with human ageing. Though there is a decline in the ability to adapt to environmental stresses with age this may be met by changes in adaptational strategy in physiological systems.     

Real-time confocal microscopic observations on human corneal nerves and wound healing after excimer laser photorefractive keratectomy

PURPOSE: Corneal wound healing after excimer laser photorefractive keratectomy (PRK) passes through a series of characteristic stages which have earlier been defined by means of histological, histochemical, and biochemical approaches. We investigated the potential of confocal microscopy to verify morphological changes in human corneas in vivo after PRK. METHODS: Ten corneas of eight patients that had earlier undergone PRK were examined at different postoperative time points (7 days-34 months). One of the PRK patients was examined sequentially three times. Three additional corneas, which had earlier undergone corneal grafting surgery and then were subjected to excimer laser photoastigmatic keratectomy (PARK), were studied as well. Seven healthy untreated corneas served as controls to define the normal morphology of human cornea. A tandem scanning confocal microscope (TSCM) was used to generate real-time images of the corneas on an S-VHS videotape. The images were either digitized and further processed or the individual video frames were produced with a video printer. RESULTS: Seven days post-PRK in vivo confocal microscopy revealed the presence of morphologically immature surface epithelial cells. Delicate nerves, activated keratocytes and deposition of extracellular light-reflecting scar tissue were perceived. The epithelium appeared normal one month post-PRK. Ongoing activation of the anterior stromal keratocytes along with extracellular scar tissue were detected. We also observed increasing numbers of regenerating subepithelial nerve leashes with somewhat twisted pattern. Highly reflective, presumably activated keratocytes were no longer detected 6-7 months post-PRK. Hypercellularity with scar tissue could still be found up to 30 months post-PRK. Only one cornea examined 34 months post-PRK showed normal keratocyte morphology and recovery of the anterior stroma. However, the morphology of subepithelial nerves was still somewhat abnormal. The two corneal grafts examined 11 or 32 months post-PARK exhibited a normal-appearing epithelium but considerable stromal hypercellularity and extracellular scar deposition. The subepithelial nerves were poorly regenerated in one eye and fairly well detectable in the other. The third graft examined 15 months post-PARK revealed the presence of enlarged surface epithelial cells and dense stromal scarring but no nerves. CONCLUSION: TSCM clinically confirms the earlier histological data on healing of excimer laser wounds. It offers a distinct improvement in the assessment of excimer laser-treated corneas, as it enables cellular details and nerves to be perceived in vivo. In addition the thickness of the stromal scar can be be measured for e.g. planning of phototherapeutic keratectomy.     

Requirement for multiple lymphocyte subsets in protection by a live attenuated vaccine against retroviral infection

STUDY DESIGN: A case report and literature review of thoracic hyperkyphosis deformity secondary to glucocorticoid-induced osteoporosis in Cushing's disease. OBJECTIVES: To identify the pathophysiology of glucocorticoid-induced osteoporosis and to outline the diagnosis and treatment options for a patient with severe spinal deformity secondary to unrecognized excess glucocorticoid activity. SUMMARY OF BACKGROUND DATA: Glucocorticoid-induced osteoporosis is seen in patients exposed to supraphysiologic levels of endogenous or exogenously administered glucocorticoids. In these patients, glucocorticoids act to suppress bone formation and increase bone resorption by indirect and direct effects. These patients have a high prevalence of trabecular bone loss, resulting in much higher rates of vertebral body collapse and pathologic fracture and thus causing an increased propensity toward kyphotic spinal malalignment. METHODS: The literature was reviewed and case reports studied. This case report highlights the pathophysiology of the disease process that caused the spinal deformity and the surgical intervention used to correct the kyphotic deformity after the metabolic problem was resolved. RESULTS: This patient has responded well to treatment and surgical intervention to correct a thoracic hyperkyphotic deformity without complication. CONCLUSIONS: Unrecognized endogenous production of glucocorticoids in Cushing's disease should be considered in young adult patients with progressive osteoporotic spinal deformities.     

The crystal structure of human procathepsin K

Cathepsin K is a cysteine protease present in human osteoclasts that plays an important role in bone resorption. Cathepsin K is synthesized as an inactive proenzyme and activated under conditions of low pH. Autoproteolytic processing of the N-terminal 99 amino acid propeptide produces the active, mature form of cathepsin K. It is presumed that the activation of procathepsin K in vivo occurs in the bone resorption pit, which has a low-pH environment. We have determined the structure of human procathepsin K at 2.8 A resolution. The structure of the mature enzyme domain within procathepsin K is virtually identical to that of mature cathepsin K. The fold of the propeptide of procathepsin K is similar to that observed in procathepsins B and L despite differences in length and sequence. A portion of the propeptide occupies the active site cleft of cathepsin K. Hydrophobic interactions, salt bridges, and hydrogen-bonding interactions are observed in the structure of the propeptide and between the propeptide and the mature enzyme of procathepsin K. These interactions suggest an explanation for the stability of the proenzyme. The structure of procathepsin K contributes to an understanding of the molecular basis of inhibition by the propeptide portion of the molecule and activation of this important member of the cysteine protease family.     

Tinnitus: etiology and management

Tinnitus is the perceived sensation of sound in the absence of acoustic stimulation. Individuals who suffer from it are commonly between the ages of 40 and 80 years. Tinnitus is often classified as objective or subjective, yet the pathophysiologic cause is still unknown. Subjective tinnitus is largely identified with hearing loss. Management of tinnitus is based on an individual approach; there is no single treatment or regimen for it.     

UVB irradiation alters cellular responses to cytokines: role in extracellular matrix gene expression

Chronic myeloid leukemia course was evaluated versus sex in 271 patients. Chronic stage involved more pronounced leukocytosis, thrombocytosis and splenomegaly in females, the latter showing higher susceptibility to anemia. As a result, treatment has to deal with a greater mass of tumor. A relatively longer survival time in males (44 and 42 months, respectively) suggest a higher effectiveness of therapy in such patients. When diagnosed, leukocytosis, thrombocytosis, enhanced splenomegaly and anemia should be regarded as factors of unfavorable prognosis.