In vitro and in vivo investigations into the biocompatibility of diamond-like carbon (DLC) coatings for orthopedic applications

Diamond-like carbon (DLC) shows great promise as a durable, wear- and corrosion-resistant coating for biomedical implants. The effects of DLC coatings on the musculoskeletal system have not been investigated in detail. In this study, DLC coatings were deposited on polystyrene 24-well tissue culture plates by fast-atom bombardment from a hexane precursor. Two osteoblast-like cell lines were cultured on uncoated and DLC-coated plates for periods of up to 72 h. The effects of DLC coatings on cellular metabolism were investigated by measuring the production of three osteoblast-specific marker proteins: alkaline phosphatase, osteocalcin, and type I collagen. There was no evidence that the presence of the DLC coating had any adverse effect on any of the parameters measured in this study. In a second series of experiments, DLC-coated cobalt-chromium cylinders were implanted in intramuscular locations in rats and in transcortical sites in sheep. Histologic analysis of specimens retrieved 90 days after surgery showed that the DLC-coated specimens were well tolerated in both sites. These data indicate that DLC coatings are biocompatible in vitro and in vivo, and further investigations into their long-term biological and tribological performance are now warranted.     

Hypertension management in patients with diabetes: the need for more aggressive therapy

OBJECTIVE: Clinical trials have demonstrated the importance of tight blood pressure control among patients with diabetes. However, little is known regarding the management of hypertension in patients with coexisting diabetes. To examine this issue, we addressed 1) whether hypertensive patients with coexisting diabetes are achieving lower levels of blood pressure than patients without diabetes, 2) whether there are differences in the intensity of antihypertensive medication therapy provided to patients with and without diabetes, and 3) whether diabetes management affects decisions to increase antihypertensive medication therapy. RESEARCH DESIGN AND METHODS: We abstracted medical records to collect detailed information on 2 years of care provided for 800 male veterans with hypertension. We compared patients with and without diabetes on intensity of therapy and blood pressure control. Intensity of therapy was described using a previously validated measure that captures the likelihood of an increase in antihypertensive medications. We also determined whether increases in antihypertensive medications were less likely at those visits in which the diabetes medications were being adjusted. RESULTS: Of the 274 hypertensive patients with diabetes, 73% had a blood pressure > or =140/90 mmHg, compared with 66% in the 526 patients without diabetes (P = 0.04). Diabetic patients also received significantly (P = 0.05) less intensive antihypertensive medication therapy than patients without diabetes. Less intensive therapy in diabetic patients could not be explained by clinicians being distracted by the treatment for diabetes. CONCLUSIONS: There is an urgent need to improve hypertension care and blood pressure control in patients with diabetes. Additional information is required to understand why clinicians are not more aggressive in managing blood pressure when patients also have diabetes.     

Alterations of K-ras and p53 mutations in colorectal cancer patients in Central Europe

Many molecular investigations of colorectal cancer (CRC) have suggested that the accumulation of specific mutations in proto-oncogenes and tumor suppressor genes regulating cell growth via signal transduction trigger the stagewise progression to malignancy. In this study, the frequency, location, and type of mutations of the K-ras proto-oncogene exon I and p53 tumor suppressor gene exons 5-8 were analyzed in colorectal carcinomas of 65 patients from Central Europe, using polymerase chain reaction (PCR)-cold single-strand conformation polymorphism (SSCP) screening and direct sequencing. The incidence of K-ras activating mutations in these Central European samples was lower (25%) compared to that obtained in American and western European populations (40-50% at least), while the incidence of p53 inactivating mutations was similar (58%). These results suggest that some other genetically linked mechanisms may play a role in CRC development and progression, and hence K-ras and p53 mutations cannot be considered to be universal genetic markers for CRC.     

Russian mutational spectrum differs from that of their Western counterparts

It has been previously noted that the hypoxanthine-guanine phosphoribosyltransferase (HPRT) mutant frequency of Russian subjects is significantly higher than age-matched Western counterparts. To further explore this difference, approximately 100 mutants collected from Russian twins reported in a previous study have been sequenced and compared to an aged-matched Western mutant dataset. The mutational spectrum of the Russian subjects was significantly different (Adams and Skopek Monte Carlo test, P = 0. 004). Curiously, this younger Russian spectrum resembles that recovered from older individuals in the West. Specifically, A:T-->C:G transversions are significantly over-represented (Fisher's Exact test, P = 0.003) in the twin spectrum as compared to the young (age 相似文献   

Acute suppurative thyroiditis in children

The ability of the thyroid gland to withstand infection is a well known phenomenon. In this regard, inflammatory disease of the thyroid gland in children is an uncommon occurrence. The frequency with which this proceeds to abscess formation is rare. Review of the literature of the past 25 years reveals only 21 reported cases of acute suppurative thyroiditis in children, only one of which has been reported in the otolaryngologic literature. We report two cases of thyroid abscess in children which initially presented as painful swellings in the lower neck. An overview of the management of these patients is detailed, including a discussion of the appropriate utilization of diagnostic studies. Demonstration of an internal fistula originating from the pyriform sinus underscores the need to consider a fourth branchial arch remnant as a possible source of infection. The importance of obtaining appropriate bacterial, fungal, and acid-fast cultures is stressed, as is the role of antibiotic therapy and definitive surgery once the diagnosis of thyroid abscess is made.     

Nasal obstruction in the neonate

At birth, the neonate is an obligate nasal breather and any compromise of the nasal passages is potentially life threatening. It is important for the otorhinolaryngologist to quickly recognize and manage even subtle constrictions or obstructions of the nasal passages in this age group. Many times the nasal airway is disregarded as the source of airway difficulty if small catheters can be passed. Conversely, the inability to pass nasal catheters is often arbitrarily diagnosed as choanal atresia or stenosis. This limited outlook can delay appropriate therapy. The differential diagnosis of nasal obstruction in the neonate is presented wit emphasis on evaluation of nasal obstruction in anatomically normal appearing noses.