Parameters of protein delivery using hydroxyapatite in simulated body fluid

Various studies have been conducted using hydroxyapatite (HA) to deliver therapeutic drugs over a long period of time. However, the rate of drug release from ceramics varies tremendously. Thus a study was designed to observe the effect of particle size, pressure, drug ratio, and the addition of a zinc stearate binder on the release of BSA from ceramics. Samples were collected every two hours for a 12 hour period. Three particle sizes were used in the study (< 38, 45-63, and 63-75 microns). Variations in particle size did not influence the release of BSA. Ceramics compressed at a pressure of 150 Mpa delivered more protein than pressures of 300 MPa, 450 MPa, and 900 MPa. Drug to ceramic ratio had the most significant effect. A ratio of 1:25 BSA to HA delivered the protein quickly whereas the 1:100 BSA to HA delivered BSA to HA delivered BSA slowly and in zero order kinetics. The addition of the zinc binder improved the quality of the composite and decreased the release rate of protein delivery when present in 5% or less of the total ceramic weight. HA ceramics can be used to deliver proteins at different rates by varying compression pressure and drug to HA ratio.

Measurement of radiation dose delivered to breast tissue during mantle field irradiation for Hodgkin's disease

The treatment of Hodgkin's disease involves mantle field irradiation. Patients with early stage (I-II) Hodgkin's are often in their 20's or 30's and can expect to live for many decades after the successful management of their disease; however, complications, including second cancers in the treatment area, occur in some survivors. Breast cancer is among the leading second solid cancers that develop in patients who have undergone mantle field irradiation. This paper attempts to determine the dose that may be delivered to breast tissue from mantle field irradiation to treat Hodgkin's disease. Utilizing an anthropomorphic phantom, thermoluminescent dosimeters (TLDs) were placed into a breast phantom constructed of Superflab and TX-150, and were irradiated with 6 MV photons. Readings from 170 TLDs in five layers of breast phantom were analyzed. The results show considerable doses reaching portions of breast tissue. In measured points under the blocks, 8-15% of the prescribed isocenter dose was delivered. For points in the primary beam, readings of up to 91% of the isocentric dose were obtained. Points in the breast near block or collimator edges also received substantial doses; upwards of 70% of the prescribed dose. Several points in the breast outside the treatment field were also measured and readings ranged from 2 to 29% of the prescribed dose. Similar patterns of dose distribution were found on computer plans; however, point-by-point comparisons were not performed. These results are compared with published reports.

Reducing a peritoneal dialysis program's cost by changing from a vendor-provided to a program-provided system for general medical supplies: significant savings in CCPD

An examination of the costs associated with outpatient chronic peritoneal dialysis prompted us to investigate the charges for general medical supplies used by patients on continuous ambulatory peritoneal dialysis (CAPD) and continuous cycling peritoneal dialysis (CCPD) in our hospital-owned, not-for-profit peritoneal dialysis program. The items used by patients to perform their dialysis exchanges and daily exit site care included 4 x 3 and 2 x 2 sterile gauze pads, antibacterial soap, masks, tape, and betadine swabsticks. The charges for these supplies when purchased from the dialysis vendor were compared with charges for the same items if purchased directly from hospital stores by the peritoneal dialysis program and then distributed to the patients. This initial analysis suggested a considerable savings if the peritoneal dialysis program provided the supplies. Based on this estimated savings, in July 1995, the peritoneal dialysis program changed from a vendor-provided to a program-provided system for general supplies used by CAPD and CCPD patients. This study examined the differences in charges expressed as $/patient-month for two periods: July 1994 to June 1995 (when all general medical supplies were provided by dialysis vendors directly to the CAPD and CCPD patients) and July 1995 to May 1996 (when the peritoneal dialysis program purchased general medical supplies from hospital stores and distributed these supplies directly to the patients). The median vendor charges for CAPD patients (n = 21 during 1994 to 1995 and n = 18 during 1995 to 1996) were not significantly different between the two periods. In fact, the charges were slightly higher during the 1995 to 1996 period ($1,264/patient-month v $1,193/patient-month during the vendor-provided period of July 1994 to June 1995, P = 0.67). The median vendor charges for patients on CCPD were significantly lower during the 1995 to 1996 period when the peritoneal dialysis program provided the general medical supplies used for CCPD ($1,110/patient-month v $1,389/patient-month during 1994 to 1995, P = 0.003). There were 30 CCPD patients during the 1994 to 1995 period and 27 patients on CCPD during 1995 to 1996. The total charges for CAPD and CCPD patients combined included dialysis vendor charges (dialysis solution, tubing, cycler rental) and charges from hospital stores. These total charges were lower in the July 1995 to May 1996 period when general medical supplies were purchased directly from hospital stores rather than from the dialysis vendors: $1,201/patient-month versus $1,360/patient-month (P = 0.03). The median hospital store charges rose slightly during the July 1995 to May 1996 period when supplies were purchased by the peritoneal dialysis program from hospital stores ($31/patient-month v $21/patient-month, P = 0.37, during the July 1994 to June 1995 period when general medical supplies were purchased directly from dialysis vendors). However, despite the rise in charges from hospital stores, an overall savings of $149/patient-month was achieved when the peritoneal dialysis program purchased and provided general medical supplies used by the peritoneal dialysis patients. This $149/patient-month equals $1,788 savings per dialysis year for each patient on peritoneal dialysis for that year. Significant savings in the cost of a chronic peritoneal dialysis program may therefore occur if less expensive sources for the general medical supplies used by CAPD and, especially, CCPD patients are found.

The successful use of pronuclear embryo transfers the day following oocyte retrieval

A retrospective analysis of results from 114 initiated in-vitro fertilization cycles utilizing pronuclear embryo transfer is presented. Patients were unselected for age or infertility criteria, constituted a continuous series and were grouped according to response to stimulation (Group 1, ideal; Group 2, suboptimal) or ovarian reserve (Group 3, poor). At 16-18 h post-insemination, embryos were scored for alignment of pronuclei and nucleoli and the appearance of the cytoplasm, generating an embryo score (ES). Transfers were performed 24-26 h post-insemination using two to six embryos with the highest ES. A corrected score was calculated (total score/number of embryos; CS). A total of 114 initiated cycles resulted in 97 oocyte retrievals with 38 clinical pregnancies (39%; 15% implantation). Pregnancy rates were significantly different between the three groups; 37 pregnancies in Group 1 (55% clinical pregnancy; 20% implantation), none in Group 2 and one in Group 3 (6%; 2% implantation: P < 0.001). The ES of transferred embryos correlated with groups. There was a strong correlation between CS and implantation and delivery rates. CS >15 resulted in a 28% implantation; 65% delivery rate. CS <14 resulted in four pregnancies, one delivered. The data show that oocyte quality and pronuclear embryo morphology are related to implantation and that pronuclear embryos can be successfully selected for embryo transfer.

A twin and family study of the association between immune system dysfunction and dyslexia using blood serum immunoassay and survey data

We conducted a study of the association between developmental reading disability (DRD) and immune disorders (ID) using both survey and immunoassay data in two separate samples of families. One sample was made up of twins and their parents and was ascertained through a population-based sampling scheme. The other sample was a set of extended pedigrees selected for apparent autosomal dominant transmission of DRD. We failed to find an association between DRD and ID in either sample, regardless of the method used to assess immune system function. Even though our twin sample provided evidence that both DRD and immune conditions were significantly heritable, there was no evidence for a genetic correlation between ID and DRD nor was there any clear indication that a special subgroup of individuals may be comorbid for these conditions because of genetic reasons. How these negative findings can be reconciled with the developmental hypothesis of Geschwind, Behan, Galaburda, and colleagues, and how they may relate to the gene locus influencing DRD that has been recently located in the HLA region of the short arm of chromosome 6 is discussed.

Constitutive activation of TCR signaling molecules in IL-2-independent Herpesvirus saimiri-transformed T cells

Both human T cell leukemia virus type I and simian Herpesvirus saimiri (HVS) transform human T cells in vitro. Although IL-2-independent growth in human T cell leukemia virus type I-transformed T cells is associated with constitutive phosphorylation of JAK/STAT kinases, we now demonstrate that different mechanisms may be responsible for the ability of HVS-transformed T cells to proliferate in the absence of exogenous cytokines. The IL-2 independence of an HVS-transformed cell line correlated with constitutive activation of protein tyrosine kinases known to be induced following TCR engagement. Thus, in these cells we observed increased phosphotransferase activity of Lck as well as constitutive tyrosine phosphorylation of the TCR-associated ZAP-70 kinase and expression of the related Syk protein tyrosine kinase. While Syk is generally not expressed in activated T cells, its introduction has been shown to enhance TCR responsiveness. These results suggest that distinct signal transduction cascades can participate in the transition of T cells to IL-2 independence.

Comfort and incidence of abnormal serum sodium, BUN, creatinine and osmolality in dehydration of terminal illness

This prospective clinical study was undertaken to evaluate the effect of spontaneous food/fluid intake on serum sodium and comfort levels in a population of terminal patients (n = 31) receiving clysis or intravenous hydration. The median and mode of serum sodium were within normal limits and 56 percent of the patients were eunatremic. There was no statistically significant difference in comfort scores between predehydration and dehydration phases, and 85 percent had an optimal comfort score. A statistically significant difference was found (p < 0.5) between mean daily comfort scores of those with normal sodium versus those with abnormal sodium; those with hypernatremia were lower but still in the top third comfort levels. Because the sodium was tested using a Chem7, we also were able to calculate the BUN, creatinine, and osmolality. These are presented and compared to other study results. The findings of this study reinforce the belief that fluid depletion in dying patients results in relatively benign symptoms, that serum sodium levels are not always altered with limited intake and that comfort levels can be maintained when the serum sodium is abnormal.

Failure of intravenous ribavirin in the treatment of invasive adenovirus infection following allogeneic bone marrow transplantation: a case report

We report a case of fatal adenovirus infection in a 37-year-old female who underwent allogeneic bone marrow transplantation (BMT) for acute myelogenous leukaemia (AML). Post BMT she developed acute grade II graft-vs.-host disease (aGVHD) requiring high-dose steroids and anti-thymocyte globulin. Additionally, her clinical course was complicated with adenovirus-associated haemorrhagic cystitis and viraemia. Intravenous ribavirin was obtained and administered for 5 days without success; the patient's mental status deteriorated rapidly and she died on day 69 post-transplant. Radiological imaging revealed diffuse cortical necrosis. At autopsy adenovirus was identified in her bladder, kidneys and lungs.

Differential affinity labeling of the two subunits of the homodimeric animal fatty acid synthase allows isolation of heterodimers consisting of subunits that have been independently modified

To explore the domain interactions that are required for catalytic activity of the multifunctional, homodimeric fatty acid synthase (FAS), we have formulated a strategy that allows isolation of modified dimers containing independently mutated subunits. Either a hexahistidine or a FLAG octapeptide tag was incorporated into the FAS at either the amino terminus, within an internal noncatalytic domain, or at the carboxyl terminus. The presence of the tags had no effect on the activity of the wild-type FAS. His-tagged dimers were mixed with FLAG-tagged dimers, and the subunits were randomized to produce a mixture of His-tagged homodimers, FLAG-tagged homodimers, and doubly tagged heterodimers. The doubly tagged heterodimers could be purified to homogeneity by chromatography on an anti-FLAG immunoaffinity column followed by a metal ion chelating column. This procedure for isolation of FAS heterodimers was utilized to determine whether the two centers for fatty acid synthesis in the FAS dimer can function independently of each other. Doubly tagged heterodimers, consisting of one wild-type subunit and one subunit in which the thioesterase activity had been eliminated, either by mutation or by treatment with phenylmethanesulfonyl fluoride, have 50% of the wild-type thioesterase activity and, in the presence of substrates, accumulate a long chain fatty acyl moiety on the modified subunit, thus blocking further substrate turnover at this center. Nevertheless, the ability of the heterodimer to synthesize fatty acids is also 50% of the wild-type FAS, demonstrating that an individual center for fatty acid synthesis has the same activity when paired with either a functional or nonfunctional catalytic center.

The malonyl/acetyltransferase and beta-ketoacyl synthase domains of the animal fatty acid synthase can cooperate with the acyl carrier protein domain of either subunit

The active form of the animal fatty acid synthase (FAS) is a dimer of identical multifunctional polypeptides, each containing seven discrete functional domains, that cooperate to form two centers for palmitate synthesis. To assess the importance of domain cooperation across the subunit interface in the reaction mechanism, we have utilized a strategy based on complementation analysis in vitro of modified FASs carrying critical mutations in specific catalytic domains. Homodimeric FASs carrying the same mutation(s) in both subunits are unable to synthesize fatty acids. As predicted by the current head-to-tail model for the animal FAS, heterodimeric FASs formed between the acyl carrier protein (ACP) mutant and either the beta-ketoacyl synthase (KS) or malonyl/acetyltransferase (MAT) are active in palmitate synthesis, confirming that the KS and MAT domains can cooperate with the ACP domain of the opposite subunit. Contrary to this model however, heterodimeric FASs formed between the KS and MAT mutants, between a MAT, ACP double mutant, and a KS mutant, and between a KS, ACP double mutant, and a MAT mutant are also active in palmitate synthesis, indicating that the MAT and KS domains can also cooperate with the ACP domain of the same subunit. The results of this study reveal an unanticipated element of redundancy in the FAS reaction mechanism in that the amino-terminal KS and MAT domains can make functional contact with the penultimate carboxy-terminal ACP domain of either subunit. A revised model for the FAS is proposed in which the substrate loading and condensation reactions can be catalyzed either by one of the two subunits or by cooperation between domains across the subunit interface.

Abrogation of Smad3 and Smad2 or of Smad4 gene expression positively regulates murine embryonic lung branching morphogenesis in culture

Smad genes are recently identified intracellular effectors for receptor signaling in the BMP/activin/TGF-beta pathway. Since TGF-beta ligands are known to inhibit embryonic lung branching morphogenesis, we tested the hypothesis that Smad genes negatively regulate lung organogenesis. Antisense oligodeoxynucleotides were designed to attenuate Smad3 and Smad2 gene expression in embryonic (E11) mouse lungs over 4 days in culture. Endogenous Smad3 and Smad2 mRNA levels were suppressed by 97 and 91%, respectively, in cultured embryonic lungs when antisense oligodeoxynucleotide (40 microM) to Smad was added, compared to scrambled and sense sequence controls. The corresponding Smad3 and Smad2 protein amounts were also decreased respectively by 86 and 90% in lungs treated with Smad3 and Smad2 antisense oligodeoxynucleotide. Phenotypically, Smad antisense oligodeoxynucleotides resulted in a concentration-dependent increase in lung branching: embryonic lung branching was stimulated by up to 53% in culture with 40 microM antisense oligodeoxynucleotide, whereas both scrambled and sense controls showed no stimulatory effect. Thus, inhibition of endogenous Smad3 and Smad2 gene expression resulted in stimulation of embryonic lung branching similar to that caused by inhibition of TGF-beta type II receptor expression and signaling (J. Zhao et al., 1996, Dev. Biol. 180, 242-257). Abrogation of Smad4 (DPC4), the downstream mediator of Smad3 and Smad2 proteins, with antisense oligodeoxynucleotide, also resulted in increased branching morphogenesis. Furthermore, while TGF-beta alone inhibited lung branching morphogenesis in culture, addition of exogenous TGF-beta 1 could not overcome the stimulatory effect on lung branching of Smad antisense oligodeoxynucleotide treatment. By immunohistochemistry, Smad proteins were localized mainly to the epithelial cells lining the branching distal airways, indicating that Smad genes could regulate lung morphogenesis through mesoderm-endoderm interaction. Our results demonstrate, for the first time, that abrogation of Smad2 and Smad3 or of Smad4 gene expression stimulated early mouse embryonic lung branching morphogenesis in culture, possibly through reversing the negative influence of endogenous TGF-beta signaling upon lung branching morphogenesis.

Postmodernity and a hypertensive patient: rescuing value from nihilism

Much of postmodern philosophy questions the assumptions of Modernity, that period in the history of the Western world since the Enlightment. These assumptions are that truth is discoverable through human reason; that certain knowledge is possible; and furthermore, that such knowledge will provide a basis for the ineluctable progress of Mankind. The Enlightenment project is underwritten by the conviction that knowledge gained through the scientific method is secure. In so far as biomedicine inherits these assumptions it becomes fair game for postmodern deconstruction. Today, perhaps more than ever, plural values compete, and contradictory approaches to health, for instance, garner support and acquire supremacy through consumer choice and media manipulation rather than evidence-based science. Many doctors feel a tension between meeting the needs of the patient face to face, and working towards the broader health needs of the public at large. But if the very foundations of medical science are questioned, by patients, or by doctors themselves, wherein lies the value of their work? This paper examines the issues that the anti-foundationalist thrust of postmodernism raises, in the light of a case of mild hypertension. The strict application of medical protocol, derived from a nomothetic, statistical perspective, seems unlikely to furnish value in the treatment of an individual. The anything goes, consumerist approach, however, fares no better. The author argues that whilst value cannot depend on any rationally predetermined parameters, it can be rescued, and emerges from the process of the meeting with the patient.