The dual-wave bolus feature in continuous subcutaneous insulin infusion pumps controls prolonged post-prandial hyperglycaemia better than standard bolus in Type 1 diabetes

The dual-wave bolus delivers a combination of an immediate normal pre-meal insulin bolus (approximately 3 min) followed by an extended (or square-wave) bolus that is evenly delivered over several hr as programmed by the patient. The purpose of this study was to compare post-prandial glycaemic excursions following a high-fat meal after administration of insulin by normal vs dual-wave bolus. During this prospective, cross-over, repeated measures study, subjects with diabetes and treated with insulin pump therapy were evaluated using the continuous glucose monitoring system (CGMS) following three combinations of meal and bolus type. A control meal or a high-fat meal was given in place of the evening meal on three separate occasions and comparisons were made between: a) the control meal with normal insulin bolus delivery, b) the high-fat meal with normal insulin bolus delivery, and c) the high-fat meal with dual-wave insulin bolus delivery. Although mean baseline CGMS values were similar in each of the three combinations of meal and bolus type (p=0.54) and in the three hr immediately following the meal (p=0.64, p=0.83, p=1.0), when compared to the control meal/normal bolus and high-fat meal/dual-wave bolus combinations, CGMS profiles disclosed significantly elevated post-prandial glucose in hr 5 through 14 (p<0.05) following the high-fat/normal bolus combination. Prolonged post-prandial glycaemic excursions are identified using the CGMS. Treating post-prandial hyperglycaemia with dual-wave insulin delivery may help manage chronic hyperglycaemia in patients with diabetes.

Electrophoretic separation of multiprotein complexes from blood platelets and cell lines: technique for the analysis of diseases with defects in oxidative phosphorylation

A two-dimensional electrophoretic technique combining blue native polyacrylamide gel electrophoresis (BN-PAGE) with Tricine sodium dodecyl sulfate (SDS)-PAGE was previously used for the localization of oxidative phosphorylation (OXPHOS) defects in human diseases starting from biopsy or autopsy tissues (Schägger, H., Electrophoresis 1995, 16, 763-770). In the present work the technique was extended for the resolution of OXPHOS enzymes from platelets and tissue-cultured cells. Silver staining is required to detect the protein subunits of OXPHOS complexes in two-dimensional gels. However, the use of cultured cells has major implications for patients with mitochondrial encephalomyopathies since it will reduce the number of invasive muscle biopsies. The ease of isolating the platelet membrane glycoprotein complex from a few milliliters of blood makes it possible to analyze this complex and its protein subunits in bleeding disorders like Glanzmann's thrombasthenia.

Clinical assessment, optic disk measurements, and visual-evoked potential in optic nerve hypoplasia

PURPOSE

Because there is a broad spectrum of visual dysfunction in eyes with optic nerve hypoplasia, we determined whether any clinical observations, including optic disk measurements, could predict visual outcome in eyes with hypoplastic optic nerves.

METHODS

We prospectively studied the eyes of 19 children (eight consecutive and 11 randomly selected), ages 7 to 92 months, in whom a diagnosis of optic nerve hypoplasia was made by an ophthalmologist. Clinical assessment included visual acuity, pupillary responses, and nystagmus. The ratio of the horizontal disk diameter to the disk-macula distance was calculated from fundus photographs. The amplitude and latency of the flash visual-evoked potential as well as the threshold response to pattern reversal checks were recorded.

RESULTS

Visual acuity was associated with pupil reactivity, nystagmus, the ratio of the horizontal disk diameter to the disk-macula distance, pattern visual-evoked potential threshold, and flash visual-evoked potential amplitude (P < .001 for all parameters). All eyes with a ratio of the horizontal disk diameter to the disk-macula distance greater than .30 had good visual acuity, and all eyes with a ratio of the horizontal disk diameter to the disk-macula distance less than .30 had poor visual acuity. No eye with a ratio of the horizontal disk diameter to the disk-macula distance less than or equal to .15 had visual acuity better than light perception.

CONCLUSIONS

Visual-evoked potential and photogrammetric measurement of relative disk size can be used to approximate visual acuity in eyes with optic nerve hypoplasia. This finding could lead to a diagnostic criterion or a severity classification for optic nerve hypoplasia.

Team approach to charting: medical staff join in

At British Columbia's Prince George Regional Hospital, collaboration between the hospital's chief of medical staff and its manager of health records has resulted in more meaningful, accurate, timely and complete patient records. The hospital departed from the traditional process of deficiency flagging to physician ownership and ultimate accountability for medical charting.

Preferential retention of paternal alleles in human retinoblastoma: evidence for genomic imprinting

The origins of the initial mutations in sporadic retinoblastoma were explored using polymorphic markers from chromosome 13q. The paternal chromosome was maintained in 3 of 3 informative bilateral tumors which had undergone reduction to homozygosity for regions of this chromosome. The paternal chromosome was maintained in 7 of 8 informative unilateral tumors which likewise demonstrated a reduction of homozygosity. These data are in contrast to previously published studies of chromosome retention in unilateral retinoblastoma [Dryja, T. P., Mukai, S., Petersen, R., Rapaport, J. M., Walton, D., and Yandel, D. W. Nature (Lond.), 339: 556-558, 1989; Zhu, Z., Dunn, J. M., Phillips, R. A., Goddard, A. D., Paton, K. E., Becker, A., and Gallie, B. L. Nature (Lond.), 340: 312-313, 1989] and provide the first evidence that genomic imprinting may play a role in this disease.

Nucleotide sequence of cDNA clones encoding the complete precursor for subunit delta of thylakoid-located ATP synthase from spinach

The nucleotide sequence of the entire nuclear-encoded precursor for subunit delta of the ATP synthase from spinach thylakoid membranes was determined by cDNA sequencing. Appropriate recombinant DNAs were selected from pBR322 and lambda gt11 libraries made from polyadenylated RNA of greening spinach seedlings. The mature protein consists of 187 amino acid residues corresponding to a molecular weight of 20468. The precursor protein (257 amino acid residues; M r=27676) is probably processed between a Met-Val bond. The predicted secondary structure of the transit sequence (70 residues; 7.2 kDa) resembles that of the Rieske Fe/S polypeptide, but shows little similarity with those of stromal or luminal proteins. The comparison of the chloroplast delta amino acid sequence with the published delta sequences from respiratory ATP synthases of bacterial and mitochondrial sources and from the thylakoid ATP synthase of the cyanobacterium Synechococcus suggests substantial divergence at the genic level although structural elements appear to be remarkably conserved.

Plastocyanin is encoded by an uninterrupted nuclear gene in spinach

Plastocyanin is a member of photosynthetic electron transport chains that transfers electrons from cytochrome f to the oxidized P700 chlorophyll a pigment of the photosystem I reaction center. We have isolated and characterized cDNA- and genomic clones from spinach (Spinacia oleracea) encoding the complete plastocyanin-precursor polypeptide. The amino acid sequence derived from the nucleotide sequence shows that the precursor consists of 168 amino acid residues including a transit sequence of 69 residues. The precursor polypeptide has a predicted Mr of 16,917, the mature protein of 10,413. The available data indicate that plastocyanin derives probably from a single-copy gene. The coding region contains no intron. The size of the mRNA as determined by S1 nuclease protection experiments is approximately 660 nucleotides, although analysis of different cDNA clones suggests that longer RNA species do exist, approaching the size of the mRNA (850 bases) estimated by Northern blot techniques.