Neuroprotection of retinal ganglion cells in DBA/2J mice with GDNF-loaded biodegradable microspheres.

This study aims to promote long-term retinal ganglion cell (RGC) survival in a spontaneous glaucoma model by injecting slow-release Poly(DL-lactide-co-glycolide) (PLGA) microspheres containing glial cell line-derived neurotrophic factor (GDNF) into the vitreous. Microspheres (1 microL) suspended in PBS were injected in ipsilateral eyes while contralateral eyes served as untreated controls. Mice were injected at 2 months intervals (1-4 injections) depending on the protocol. ELISA assay indicated a cumulative GDNF release of 35.4 ng/mg over 71 days. The release was nonlinear with an initial burst of over 50%. Mice displayed a 30% drop in RGC density by 8 months (p = 0.013) and 80% drop by 10 months (p < 0.01). GDNF delivery increased RGC survival in all groups. Mice receiving early treatment showed up to 3.5 times greater RGC density than untreated mice at 15 months survival (p < 0.05). No significant effect was found in sham or lens injury groups. Microsphere-delivered GDNF significantly increases long-term RGC survival in a spontaneous glaucoma model, although the nonlinear release kinetics suggest that burst release may play a role in this rescue. Neuroprotection with slow-release polymers with improved release kinetics should be further studied as a potential therapy for glaucoma and other diseases involving the loss of central nervous system neurons.

Femoral neck-shaft angle in extra-capsular proximal femoral fracture fixation; does it make a TAD of difference?

The effect of femoral neck-shaft angle and implant type on the accuracy of lag screw placement in extra-capsular proximal femoral fracture fixation was investigated. Radiographs of all extra-capsular proximal femoral fractures seen in one unit over 18 months were reviewed. Of 399 cases, 307 (237 female, 70 male) were included in the study as they had no contra-lateral proximal femoral metal work. Femoral neck-shaft angle (NSA) of the uninjured hip and magnification adjusted tip-apex distance (TAD) of femoral head lag screw were measured. Type of fixation implant was 135 degrees classic hip screw (CHS) (n=144) or 130 degrees intra-medullary hip screw (IMHS) (n=163). Mean contra-lateral NSA was 130.2 degrees (112.9--148 degrees ) and 64 patients (58 female, 6 male) had a NSA <125 degrees . Mean adjusted TAD was 18.7 mm (5.8--43.8mm) and 88.9% of cases had a TAD of less than 25 mm. TAD values were significantly greater using an IMHS if NSA was <125 degrees than if NSA was >125 degrees (p=0.028). This was not the case with the CHS. The use of the 130 degrees -IMHS in patients with a NSA <125 degrees leads to poorer lag screw placement than if NSA >125 degrees and caution is advocated when using this device in such cases.

Mycobacterial infection: a difficult and late diagnosis in stem cell transplant recipients.

The Infectious Diseases Working Party of the European Blood and Marrow Transplant Group conducted a survey to obtain information about the frequency, presentation, and treatment of mycobacterial infection (MBI) in stem cell transplant (SCT) recipients. Among 29 centers, MBI was diagnosed in 0.79% of 1513 allogeneic and 0.23% of 3012 autologous SCT recipients during 1994-1998 a median of 160 days after transplantation. The mean interval between first symptoms and diagnosis was 29 days and was still longer for patients with atypical MBI or recipients of corticosteroid therapy. The prevalence of MBI was highest among those who received matched unrelated or mismatched STCs from related donors. Of 31 patients, 20 had tuberculosis, 8 had atypical MBI, and 3 had diagnoses based on histological findings only. Five patients (16%) died, all of whom had received an allogeneic SCT. Because of the increased numbers of unmatched donors and transplantation programs in countries with a high prevalence of tuberculosis, constant vigilance is required to early detect MBI in SCT recipients.

Comparison of energy-minimized structures of [Pd(II)(N-methyliminodiacetate)] complexes of X(1)-His-X(3)-His-His peptides as an analysis of steric and specific interactions with synthetic binding tags for IMAC separations.

[Pd(II)(mida)(peptide)] complexes for the series of peptides of sequence X(1)-His-X(3)-His-His were studied by molecular mechanics methods using Spartan, MMFF94, and SYBYL programs with X(1) = X(3) = glycine (G), phenylalanine (F), tyrosine (Y), tryptophan (W), and with X(1) = glycine (G) and X(3) = proline (P). For comparison purposes, data were also obtained for the Ser-Pro-His-His-Gly (SPHHG) and the (His)(5) peptides.The latter two peptides and GHPHH are tags in current use for IMAC separations. These provide calibration points as to the binding affinities that have been determined for the entire series. The energies of the complexes, as an average trend found from the composite behavior of the three methods, were found to be SPHHG (205 kcal/mol) (most stable; are values obtained by MMFF94 methods) < HH(#)HH(#)H(#) (222; where # implies the site of attachment to match the other X(1)-His-X(3)-His-His peptides) < YHYHH (249) < GHGHH (265) < WHWHH (284) approximately GHPHH (286) < FHFHH (311) (least stable), implying that FHFHH might be a useful chromatographic tag for IMAC protein separations that would elute more readily than GHPHH from IMAC sites that are of square-planar structure, such as Cu(II)(ida-supported) IMAC columns. Specific H-bonded interactions are observed between the tyrosine X(1) and pendant carboxylates and between X(3) and the N-terminal amine of [Pd(mida)(YHYHH)]. Face-to-pi-face ring stacking occurs between phenylalanine X(1) and X(3) units in [Pd(mida)(FHFHH)], whereas edge C-H to pi H-bonding or pi stacking occurs between the X(1) and X(3) tryptophans of [Pd(mida)(WHWHH)]. Two energy minima were found with tryptophan. The more stable form has the aromatic rings more parallel, similar to the stacked form of phenylalanine, rather than the edge C-H to pi H-bonding, and virtually the same overall energy as for [Pd(mida)(GHPHH)]. The "perpendicular" structure was found as an initial local energy minimum, but additional MMFF94 calculations found the pi -stacked arrangement at energy ca. 39 kcal/mol lower than that of the nearly "perpendicular" arrangement of the tryptophan rings, a composite effect of relaxation of the peptide, together with differences in stabilities imparted by the differing geometries. The use of the terms "pi-stacked " and "perpendicular" forms represent the limiting cases available to the tryptophan side chain groups. A twist of about 15 degrees to 20 degrees in dihedral angle is all that is necessary to change between structures that are nearly described as one form or the other.

Mycobacterial central venous catheter tunnel infection: a difficult problem.

We report our experience of non-tuberculous mycobacterial infection associated with the tunnel of Hickman-Broviac central venous catheters in immunosuppressed patients with haematological malignancies undergoing high-dose chemotherapy supported by BMT. The problem is rare and difficult to treat. Our cases are unique in developing tunnel site mycobacterial infection well after the tunnelled catheters were removed. We diagnosed one case of Mycobacterium chelonae, which is a well-documented cause of such infections, and two cases of Mycobacterium haemophilum, which are the first reported cases in this setting. Early wide surgical excision of the infected tunnel site and prolonged antibiotic therapy is necessary. Despite these measures recurrence occurred in two cases. Close liaison with the microbiology laboratory is needed to ensure the appropriate culture media and conditions are used for these fastidious organisms. Empiric antibiotic regimens should be based on the likely organism. Drugs active against M. chelonae and M. haemophilum should be included.

The use of flow cytometry in the diagnosis and monitoring of malignant hematological disorders.

Flow cytometry is a modality with ever increasing application in modern hematological practice. This is due to the rapidity of obtaining results, ease of use and increasing power to detect abnormal populations of cells. The major uses of flow cytometry in malignant hematology are in the diagnosis, classification and monitoring of diseases such as leukemia, lymphoma and myeloma. The technique is now used also to detect disease-specific populations of cells in paroxysmal nocturnal hemoglobinuria. This review describes the use of flow cytometry in many disease states.

Axon-target interactions in the developing cerebellum.

After entering target regions, afferent growth cones grow among putative target cells, stop extending upon meeting target cells, and transit into a synaptic ending. During these events, signals are transmitted to and from target cells to stimulate programs of differentiation. Here we describe three approaches to unraveling mechanisms of these phases of synaptogenesis. First, dye-labeling in the intact cerebellum has revealed the orchestration of afferent ingrowth and contacts with target cells. Second, an in vitro model based on purified granule neurons has shed light on the role of target cells in the arrest of afferent extension. Third, coculture of purified granule neurons (parallel fiber afferents) with purified Purkinje cells has demonstrated facets of afferent regulation of target cell differentiation. These analyses have suggested molecular mechanisms that mediate maturation of afferents and their targets.

Lead poisoning in an electrician: a bad substitute for a bad habit.

An electrician presented with a four-month history of unexplained abdominal pain and constipation, which had prompted four hospital admissions and numerous investigations. Blood-film results suggested lead poisoning, and an occupational history revealed that he had chewed about a metre of electrical cable (which contains lead) daily for 10 years as a substitute for smoking.

Diabetes mellitus in adolescents: a comprehensive approach to outpatient care.

A comprehensive approach to care of adolescents with diabetes mellitus requires knowledge of the unique characteristics of juvenile diabetes during this development period, appropriate medical goals, and awareness of the numerous psychologic and social problems encountered. Involvement of other health professionals is frequently needed. Successful adjustment of the adolescent to having diabetes includes absence of "maladaptive" coping mechanisms, realistic future goals, and acceptance of responsibility for self-care.

The relationship of serum alkaline phosphatase concentrations to sex maturity ratings in adolescents.

The relationship of serum alkaline phosphatase concentrations to sex maturity ratings, age sex, and race was studied in healthy prepubertal and adolescent patients. Previous data concerning SAP concentrations in adolescents have been age related and do not give primary consideration to biologic growth during adolescence. The highest mean concentrations for girls occurred at SMR 2 and for boys at SMR 3, coinciding in each instance with peak height velocity and thus correlating with presumed maximum osteoblastic activity during growth. With increasing SMR or age, the SAP levels in both sexes decreased markedly. Black boys had higher SAP concnetrations than white boys at SMRs 2, 3 and 4, whereas black girls had higher values than white girls only at SMR 4. This study demonstrates the value of correlating the enzyme activity with sex maturity ratings rather than with chronologic age.