Yeast-derived recombinant human insulin-like growth factor I: production, purification, and structural characterization

Recombinant human insulin-like growth factor I (IGF-I) is efficiently expressed and secreted from Saccharomyces cerevisiae using a yeast alpha-factor leader to direct secretion. However, approximately 10-20% of the IGF-I was in a monomeric form, the remaining materials being disulfide-linked aggregates. When the purified material was subjected to reverse-phase high-performance liquid chromatography (rp-HPLC), it gave two doublet peaks, I and II. Upon reduction, doublet peaks I and II converged to one doublet peak. This suggests that peaks I and II result from different disulfide structures, and the doublet feature of each peak results from other causes. Different disulfide structures between peaks I and II were also suggested from the near UV circular dichroism of these proteins. Only the peak II was biologically active, indicating that peak II has the correct disulfide structure. Concanavalin A affinity chromatography of the purified peak II doublet showed binding of the subpeak with an earlier rp-HPLC retention time, indicating that it was glycosylated. Sequence analysis of tryptic peptides suggested that Thr29 was the site of glycosylation. Site-directed mutagenesis was used to convert Thr29 to Asn29. This substitution reduced, but did not eliminate IGF-I glycosylation, suggesting additional glycosylation sites. The site of carbohydrate addition was consistent with the model that O-glycosylations occur on hydroxyl amino acids near proline residues in beta-turns.

Secretion of glycosylated human erythropoietin from yeast directed by the alpha-factor leader region

The pre-pro alpha-factor leader region of the yeast MF alpha 1 gene was used to direct the secretion of the human glycoprotein, erythropoietin (EPO), into the culture medium. An examination of the role of expression level on secretion of biologically active EPO indicated that there are several rate-limiting steps. These include processing of the alpha-factor-EPO precursor protein by the KEX2-encoded endoproteinase and transport of the protein through the secretory pathway. The rate-limiting steps for transport were early in the secretory pathway, probably from the endoplasmic reticulum to the Golgi apparatus.

Chronic central vein catheterization for intraoperative and long-term venous access in swine

Chronic venous access and repeated blood sampling for research purposes in large swine ideally should be possible without sedation, restraint or direct venipuncture of deep vessels. An operative technique of cranial vena cava catheterization and chronic catheter maintenance methods are described which were used successfully in the placement of 11 silicone rubber catheters in 10 animals. All were used for repeated blood sampling, as well as intraoperative infusion of medications and large fluid volumes. Long term patency was excellent with 10 catheters patent at the end of the study interval, up to 14 weeks after insertion. Serial blood sampling was accomplished easily without restraint. Catheter damage, infection or malfunction was rare. Proper maintenance and careful aseptic blood sampling render the cranial vena cava catheter a safe and reliable alternative to direct venipuncture in swine.

Atlantoaxial instability and abnormalities of the odontoid in Down's syndrome

Radiography of the lateral neck was performed on all children with Down's syndrome aged 4-15 in the Southern Derbyshire health district (n = 67) and a random selection of adults (n = 94). Atlantoaxial instability, defined as a gap of over 4 mm, was present in seven (10%) children and two (2%) adults. Odontoid hypoplasia, defined as an odontoid peg two standard deviations below the mean in an age matched population, was present in 15 (22%) children and 14 (15%) adults, with accessory odontoid ossicles present in two (2%) and two (3%) respectively. No one was found to have symptoms or clinical signs of spinal cord compression. Atlantoaxial instability was therefore found to be commoner in children than adults. Different programmes of management are suggested, in terms of regular clinical examination for signs and symptoms and by radiographic screening. Particular care should be taken with those who have both atlantoaxial instability and odontoid hypoplasia or accessory ossicles as they are at particular risk of spinal cord damage.

The odontoid process in children--is it hypoplastic?

An analysis of the cervical spine of 508 normal children aged between 3 and 18.9 years provided data for the normal development of the odontoid process and its relationship to the anterior arch of the atlas. In normal children under the age of 9 years, the tip of the odontoid may fall well short of the upper margin of the anterior arch of the atlas. This has important implications for the assessment of atlanto-axial instability in children with Down's syndrome.

Bone scintigraphy in the assessment of spondylolysis in patients attending a sports injury clinic

Thirty-three patients attending the Nottingham Sports Injury Clinic in whom a clinical diagnosis of a stress fracture of the pars interarticularis was made were evaluated with both radiography and bone scintigraphy. This was done in an effort to distinguish a recent stress fracture which would produce a positive scintigram from an established 'incidental' spondylolysis giving a normal scintigram. Nine patients demonstrated abnormal radiography with a normal scintigram. A further nine patients had a positive scintigram. Six were associated with a spondylolysis indicating a recent stress fracture but two had normal radiography suggesting a stress fracture in the 'sub-radiological' phase. One patient had increased uptake in relation to degenerative changes of the lower lumbar facet joints. Oblique views of the scintigram helped in localisation of the abnormal uptake to the pars interarticularis.

The medicinal plants of Gunung Leuser National Park, Indonesia

This paper describes an ethnopharmacological study of two remote settlements in Indonesia. Interviews with practitioners of traditional medicine (dukuns) were carried out to determine the vernacular names of plants used for medicinal purposes. Parts used, methods of preparation and the medicinal uses of 158 species are presented in an inventory. Samples from several species are currently undergoing chemical analysis.

Short- and long-term effects of furosemide on lung function in infants with bronchopulmonary dysplasia

Although furosemide improves lung mechanics in some infants with broncho-pulmonary dysplasia (BPD), this may not be important unless gas exchange also improves. To determine the relationship between improvement in mechanics and improvement in gas exchange, the short- and long-term effects of furosemide therapy were studied in 16 spontaneously breathing infants with severe BPD who were both oxygen dependent and hypercarbic (mean PCO2 54 +/- 11 torr). Each infant was examined at least three times: before furosemide therapy, 1 hour after the first dose of furosemide, and after a 6- to 10-day course. Ten of the 16 infants were also examined three times during a 7-day control period. Transcutaneous PO2 and PCO2, esophageal pressure, air flow, and tidal volume were measured. Pulmonary resistance, lung compliance, and the alveolar to skin PO2 difference were calculated. After a single dose of furosemide, only compliance significantly improved. After prolonged therapy, compliance, resistance, and oxygenation significantly improved in the group as a whole, but better oxygenation was achieved in only six of 16 infants. tcPCO2 was unaffected by long-term furosemide therapy, but in all infants with decreased tcPCO2 1 hour after a single dose, there was sustained decrease in PCO2 after prolonged therapy. Changes in gas exchange were not explained by changes in lung mechanics. These data indicate that long-term diuretic therapy can improve the mechanical properties of the lungs of spontaneously breathing infants with BPD, but that gas exchange is usually unaffected.

The urographic appearances of ureteric obstruction secondary to bladder carcinoma

It is usually assumed as a result of experiments that post-obstructive and hydronephrotic atrophy are due to raised intrapelvic pressure. In acute ureteric obstruction raised intrapelvic pressure is associated with renal colic; the absence of pain in chronic obstruction has been a stumbling block to acceptance of the back pressure theory. In ureteric obstruction due to bladder carcinoma the complete spectrum of nephrographic appearances ranging from those of high pressure obstruction to low pressure obstruction is seen in the absence of pain. This shows that acute ureteric obstruction may be painless and therefore post-obstructive and hydronephrotic atrophy may be preceded in man by a raised intrapelvic pressure. This removes the stumbling block.

Scanning electron microscopy of antigen induced arthritic joints. I. Inflammatory cell interactions at synovial-meniscal surfaces during the Arthus response

Scanning electron microscopy has been used to study experimental antigen induced arthritis, providing a unique perspective of the early inflammatory events. An initial aggregation of acute inflammatory cells was noted at the synovial-meniscal junction with maximal numbers observed between 12 and 24 h post challenge. Variations in cell surface ruffling, which may represent different phases of activation, were observed throughout the Arthus response. By 48 h post challenge the meniscal and synovial surfaces were covered by a mat of fibrin and degraded cell remnants.

Isolation and characterization of the structural gene for secreted acid phosphatase from Schizosaccharomyces pombe

The Schizosaccharomyces pombe acid phosphatase structural gene (PHO 1) was isolated by complementation of an S. pombe acid phosphatase mutant with a wild type S. pombe DNA recombinant plasmid library. Northern analysis indicates that acid phosphatase is encoded by a 1.4-kilobase mRNA of which approximately 100 bases are 3'-poly(A). The gene contains no introns and the 3' and 5' untranslated regions are short. According to DNA and amino acid sequence data, the S. pombe acid phosphatase has a molecular weight of 50,600. An 18-amino acid sequence at the N terminus was found that is similar to previously identified signal peptides in other eukaryotic secretory proteins. This signal peptide is apparently removed during secretion, since it is absent in the mature secreted acid phosphatase. The gene can be induced 2--3-fold by starvation for phosphate. The signals required for this induction are contained on the isolated DNA clone. Although the gene can be expressed in Saccharomyces cerevisiae, secretion is abnormal.

Spontaneous intramural oesophageal dissection

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Descriptive anatomy of fibrocartilaginous menisci in the finger joints of the hand

Observations were made from the dissection of 156 digital joints (thumbs excluded). In all joints fibrocollagenous menisci projected into the articular cavity from a ring-like structure based on the joint capsule. These meniscal structures separated the articulating cartilage surfaces at the margins of the joint. Histological examination confirmed a fibrocartilaginous nature of the tissue which demonstrated positive staining for proteoglycans and collagen fibers. Although generally similar in form, these meniscal structures varied in extent when compared between joint groups. The greatest amount and articular contribution was noted in metacarpophalangeal joints with least being found distally.

Immune complex mediated destruction of cartilage in antigen-induced arthritis of rabbits

Antigen-induced arthritis of rabbits is used as a model to study pannus-free destruction of cartilage in rheumatoid arthritis (RA) by transmission and scanning electron microscopy, incorporating plain and immune labeling techniques. During the acute "arthus" phase of the RA, immune complexes form and persist in these tissues. We observed the progressive formation of electron dense material rich in immune complexes within a millimicron of the hyaline cartilage surfaces that preceded erosion and loss of surface tissue. Polymorphonuclear neutrophils congregated at the cartilage margins to engulf immune complexes at and within the cartilage surfaces. The changes occurred in regions of hyaline and fibrocartilage free of pannus. Immune complex formation appeared to be a central feature of the cartilage destructive changes, and may be central to mechanisms of tissue loss and similar to those observed in RA.

Clinical considerations in the interpretation of auditory brainstem response audiometry

Auditory brainstem response (ABR) audiometry which monitors the electrical activity of the auditory nerve and brainstem nuclei, has provided a new technique in the diagnosis of neurological dysfunction and peripheral hearing deficits. Brainstem potentials consist of seven waves, each separated in latency by approximately one millisecond and each representing successively higher order neuron activity of the auditory pathway. The criteria used for ABR interpretation are based primarily on the latency of individual were peaks and their interpeak latencies. Due to its consistency and stability, the fifth wave has been considered prominent in the interpretation of auditory threshold sensitivity. Unfortunately, Wave V latency-intensity function may be affected by extrinsic and intrinsic variables. Consequently, in order to establish diagnostic criteria that are comparable, the elimination and/or control of these variables must be examined. Therefore, the purpose of this paper is to report the effects of various pathological and nonpathological conditions which contribute to difference in ABR audiometry interpretation.