Increased response of renal perfusion to the antioxidant vitamin C in type 2 diabetes.

BACKGROUND: Reactive oxygen species play a major role in the development of endothelial dysfunction. It is as yet unspecified whether increased oxidative stress contributes to endothelial dysfunction of the renal vasculature in patients with type 2 diabetes. METHODS: Renal haemodynamics were studied in 20 patients with type 2 diabetes and arterial hypertension (age 62 +/- 5 years) and 20 non-diabetic hypertensive patients at baseline and following infusions of the nitric oxide synthase inhibitor, N(G)-monomethyl-L-arginine (L-NMMA; 4.25 mg/kg); the substrate of nitric oxide synthase, L-arginine (100 mg/kg); and the antioxidant, vitamin C (3 g, co-infused with L-arginine 100 mg/kg). RESULTS: The response of renal plasma flow (RPF) to L-NMMA (-54 +/- 62 and -45 +/- 42 ml/min/1.73 m(2); P = NS) and L-arginine (+46 +/- 36 and +49 +/- 25 ml/min/1.73 m(2); P = NS) was not different between diabetic and non-diabetic patients. In contrast, vitamin C induced a more pronounced increase in RPF in diabetic than in non-diabetic patients when co-infused with L-arginine (+71+/-47 and +43+/-33 ml/min/1.73 m(2); P<0.05). CONCLUSIONS: The difference in the response of renal perfusion to an antioxidant suggests increased formation of reactive oxygen species and thereby reduced nitric oxide bioavailability in the renal vasculature of patients with type 2 diabetes.     

Tissue engineering of bone for mandibular augmentation in immunocompetent minipigs: preliminary study.

Large mandibular defects caused by trauma, infection or resection of a tumour are still a major problem for plastic and maxillofacial surgeons. The modern concept of tissue engineering combines the osteoinductive effects of osteogenic cells with a suitable scaffold structure to promote differentiation of osteoblasts and optimal matrix production. Critical size mandibular bone defects were therefore made to investigate the osteogenic potential of periosteal cells and a bioabsorbable polymer fleece (Ethisorb 510) in minipigs. Periosteal cells were isolated from four minipigs, expanded in vitro and seeded with fibrin glue into Ethisorb 510 fleeces. Tissue constructs were used to repair critical size mandibular defects and compared with two minipigs with untreated bone defects. Bone healing was evaluated after 90 and 180 days by radiographs and a histological scoring system. The radiographs showed increased radiodensity of defects filled with the cell-fibrin-fleece-constructs compared with the untreated control group after 90 and 180 days in vivo. The defects repaired by the cell-fibrin-scaffolds (180 days in vivo) obtained the highest histological mean score 2.9 (range 2-3), while defects filled by cell-fibrin-scaffolds (90 days in vivo) achieved a mean score of 2.1 (range 2-3). In contrast, the control group (n = 2) scored 1 and 2. The results show that a combination of periosteal cells and polymer fleeces may be a promising approach for clinical mandibular augmentation.     

Ewing's sarcoma of the femur: Prognosis in 69 patients treated by the CESS group

We reviewed the treatment outcome of 69 patients with Ewing's sarcoma of the femur. The patients received chemotherapy according to the CESS 81 (n 14), CESS 86 (n 43), and CESS 91P (n 12) protocols. The 10-year relapse-free survival rates were 36%, 65%, and 65% (p = 0.01). 68 patients received local treatment. The primary tumor was treated by surgery without radiotherapy in 28 patients; 1 developed a local recurrence and 7 metastases. 10 patients received radiotherapy alone; 4 developed metastases and 4 local recurrences and metastases. 30 cases had a combination of surgery and radiotherapy; 7 developed metastases and 1 a local recurrence and metastasis. The survival of patients after radiotherapy alone was worse than that of patients after surgery with/without radiotherapy (p = 0.005). Pathological fractures (n 16) did not influence the prognosis.     

Alcohol effects on the percentage of beta waves in the electroencephalograms of twins

Electroencephalogram (EEG) recordings were made from 26 pairs of monozygotic (MZ) and 26 pairs of dizygotic (DZ) adult male twins, before and after alcohol ingestion. After a baseline EEG and a light breakfast, 1.2 ml/kg of ethanol was given orally over 15 min and the EEG repeated four times at hourly intervals. Alcohol caused a significant drop in the percentage of beta waves (14-30 cycles/sec) during the 1st hr. For the percentage of beta waves in 38 pairs of twins with complete data, MZ twin beta-wave intraclass correlations (RMZ) ranged between 0.85 and 0.91 before and after alcohol, but the DZ intraclass correlations (RDZ) started at 0.54 and fell to 0.05 at 2 hr after alcohol before recovering to baseline levels. These correlations resulted in heritability estimates [2(RMZ-RDZ)] of 0.68 at baseline and 1.73 at 2 hr. A heritability of 1.43 was found for the 1st hr drop in percentage of beta waves (RMZ = 0.78, RDZ = 0.06). These unrealistically high heritabilities, due to RDZ's approaching 0.0, suggest a failure of assumptions in the linear twin model that was used. Also, these findings are similar to, but more exaggerated than, findings in resting EEG's and visually evoked EEG potentials of twins and are compatible with the influence of gene interactions.     

Demonstration of extrachromosmal DNA fromBabesia equi merozoites

An extrachromosomal nucleic acid element was detected in high-molecular-weight DNA preparations formBabesia equi merozoites. This extrachromosomal element was shown to be DNA rather than RNA and had an apparent fragment size of about 9 kilobasepairs (kb). Hybridization experiments using purified 9-kb DNA as a probe revealed sequence homologies with extrachromosomal DNA from two otherBabesia species.     

Immunology

A selection of interesting papers that were published in the two months before our press date in major journals most likely to report significant results in immunology.     

Image-guided aspiration of solitary occult breast 'cysts'.

During the 30-month period from March 1, 1988, through August 31, 1990, image-guided aspirations of 183 solitary occult breast masses, which were considered possible cysts, were performed. Indications for aspiration included (1) mass on mammography, either invisible on ultrasonography or with features atypical of a cyst, in 111 patients; (2) enlarging solitary mass on mammography with ultrasonic features suggesting a cyst in 45 patients; and (3) mammographic mass with features typical of a cyst in 27 patients, with confirmation requested by the referring physician. Of the group, 151 (83%) lesions were fluid-filled and 32 (17%) were solid. All aspirates had normal cytologic features. Of the 32 aspirates found to be solid, 19 were subsequently removed after wire localization and 13 were unchanged on mammography for a minimum of 6 months after aspiration. This is a simple and safe procedure, confirming the innocuous nature of an occult solitary breast cyst, and obviates the need for surgical biopsy.