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PubMed1975

[The unspecific reaction of inflammation in rickets due to lack of vitamin D (author's transl)].

10 children (3--18 months old) with Vit. D Deficiency Rickets were investigated by Rebuck skin windows for their ability to elicit unspecific inflammation before and after therapy. Differences to a control group (13 children) were statistically significant. In the acute phase of the disease beginning of inflammation is retarded, reduction of polymorphonuclear leucocytes in favour of mononuclear cells is less then in controls, the absolute quantity of exsudation is reduced too. After therapy inflammation is intensified and accelerated, but exsudation is still different from control children qualitatively and quantitatively. These findings add new facts to the data already known on impaired defence mechanisms in rickets.

Female↗

PubMed1981

Altered tissue content and cytosol distribution of trace metals in experimental diabetes.

An insulin-dependent diabetic condition was induced in male Sprague-Dawley rats by streptozotocin injection. Ten days after administration of the diabetogenic drug, tissue levels of copper, zinc, iron and manganese were determined and compared to control animals. Increased quantities of hepatic copper, zinc and manganese, renal copper and zinc and plasma zinc were observed in the diabetic group. Intestinal, muscle and spleen contents of the metals were similar in control and diabetic rats. Elevated levels of zinc- and copper-metallothionein were found in liver and kidney of diabetic rats. The distribution of zinc among soluble proteins in the diabetic liver was also content of tissues, intracellular distribution of zinc and the quantity of zinc-and copper-metallothionein to normal levels. Pair-feeding copper, zinc, iron and manganese to diabetic and control groups demonstrated that the enhanced food consumption of the diabetic rat was not a significant factor in the observed accumulation of trace metals in liver and kidney. These data suggest that the hormonal imbalance characteristic of the insulin-dependent diabetic condition influences trace metal metabolism. These studies also demonstrate the usefulness of the streptozotocin-diabetic rat as an animal model for investigations concerning hormone-mediated regulation of trace metal metabolism.

Animals↗

PubMed1998

Changes of platelet cytoskeletal proteins following platelet aggregation induced by collagen and platelet membrane glycoprotein in Japanese black cattle with delta-storage pool deficiency.

Five Japanese Black cattle showing the tendency of persistent hemorrhage were diagnosed as delta-storage pool deficiency because of lack of dense bodies in platelets. There was no significant difference in the platelet count, fibrinogen concentration, prothrombin time and activated partial thromboplastin time between the cases and normal control cattle. However, the maximum platelet aggregation rate and the values of myosin in the cytoskeletons during platelet aggregation induced by collagen were significantly lower in the cases compared with those in normal control cattle. The quantities of platelet membrane glycoprotein were in the range of 94-160 kDa and were not different between the cases and control cattle. However, a decrease of thrombospondin in alpha-granules in platelet cytoplasm were suspected in two of the 5 cases.

Animals↗

PubMed1983

Evidence for defective osteoblastic function. A role for alcohol and tobacco consumption in osteoporosis in middle-aged men.

In a group of 11 men ranging in age from 35 to 50 years with idiopathic osteoporosis, most were mild alcoholics and heavy smokers. Two had absorptive hypercalciuria. Histomorphometry showed that the patients had low trabecular bone volume and mean trabecular thickness when compared with age-matched control subjects. Mean wall thickness was also markedly reduced in patients as compared with control subjects. The quantity of resorbed bone was extrapolated from the calculated mean interstitial bone thickness. Resorption was not significantly different in patients and control subjects. Consequently, in this group of patients with severe osteoporosis, the pathogenesis was characterized by markedly decreased bone formation.

Adult↗

PubMed1993

The influence of major trauma on the regulatory levels of interleukin-1 (IL-1) and IL-2 in human mononuclear leukocytes.

The monokine Interleukin-1 (IL-1) and the lymphokine IL-2 are playing a crucial role within the course of an intact cell mediated immune response (CMI). It was the objective of this study to further elucidate the cytokine associate mechanisms of dysfunctional T-cell activation following major burn and mechanical trauma. Via comparative analysis of mRNA expression and protein release the major regulatory levels of IL-1 and IL-2 release under stressful conditions were to be determined in mitogen respectively LPS stimulated PBMC (peripheral blood mononuclear cells) cultures on consecutive days (D) 1, 3, 5, 7 and 10 post injury. Further, we wanted to scrutinize if inadequate IL-2 production post-trauma is possible due to a defective transduction of extracellular signals to the T-cell nucleus. In order to answer this question IL-2 mRNA expression and IL-2 protein releases were determined in PBMC cultures using the phosphokinase C (PKC) activator phorbol ester (PMA) as a costimulus together with PHA. When analyzing the cumulative data for IL-1 beta we saw until D 5 post-trauma a considerable impairment of the protein release in LPS stimulated PBMC cultures and recovery thereafter. In only a few individual PBMC cultures we saw a concurrence between the IL-1 beta mRNA signal intensity and the protein production. In the majority of the autoradiographies analyzed, the mRNA expression for IL-1 beta was considerably more distinct compared to controls while the corresponding protein release values were on control level or below. These results implicate that the suppression of IL-1 beta post-trauma is regulated mainly on a posttranscriptional level. Since Prostaglandin E2 (PGE2) has been found to have a vigorous impact on the IL-1 beta synthesis on the translational level, we assume that the high PGE2 levels post-trauma inhibit--via cAMP--sufficient IL-1 beta synthesis on the posttranscriptional level. IL-2 protein synthesis as well as mRNA expression in mitogen (PHA) stimulated PBMC cultures following trauma, was persistently and significantly depressed compared to controls during the time of observation. The addition of PMA as a costimulus to PHA, could induce very distinct mRNA signals for IL-2 with a signal intensity which was comparable to that found in the cells of healthy controls. Also the quantity of IL-2 protein release in the vast majority of all patients PBMC cultures following PHA/PMA induction was within the control range.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗

PubMed2004

[Influence of interventional radiotherapy for severe postpartum hemorrhage on postpartum menorrhea].

OBJECTIVE: To discuss the influence of interventional radiotherapy for treating severe postpartum hemorrhage on postpartum menorrhea. METHODS: From Mar. 1995 to Feb. 2002, 18 cases of severe postpartum hemorrhage treated with arterial embolization served as the interventional group. Twenty parturients without postpartum complication were recruited as control group. The continuance of lochia, recovery of menorrhea between the two groups were compared. Serum follicle-stimulating hormone (FSH), luteinizing hormone (LH), estradiol (E(2)) of the non-lactating women in the two groups were assayed during the 3rd-5th days of the first menstrual cycle. RESULTS: Continuance times of lochia were (33.9 +/- 2.0) days, and (36.2 +/- 3.1) days in interventional group and control group, respectively. Recovery times of menorrhea were (75 +/- 17) days, and (95 +/- 16) days in interventional group and control group. The quantity of the postpartum menorrhea was 1.3 +/- 0.1 times of that before delivery in interventional group, 1.3 +/- 0.2 times of that in control group. The number of menstrual cycle before recovery to normal menorrhea was 2 cycles in interventional group, 1.9 cycles in control group. Postpartum menstrual cycle was (33.9 +/- 2.2) days in interventional group, (33.2 +/- 1.6) days in control group. Serum FSH, LH, E(2) of the non-lactating women during the 3rd approximately 5th days of the first menstrual cycle were (5.2 +/- 1.1) U/L, (7.5 +/- 1.6) U/L, (262 +/- 14) pmol/L in interventional group, (4.3 +/- 2.1) U/L, (6.3 +/- 1.3) U/L, (280 +/- 12) pmol/L in control group. There was no significant difference between the two groups (P > 0.05). CONCLUSIONS: No obvious influence of interventional radiotherapy for postpartum hemorrhage on postpartum menorrhea was observed.

Adult↗

PubMed2005

Transdermal delivery of flurbiprofen: permeation enhancement, design, pharmacokinetic, and pharmacodynamic studies in albino rats.

The enhancing effects of lemon oil on the transdermal penetration of flurbiprofen through rat skin invitro and in vivo was investigated. The maximum flux achieved by Isopropyl alcohol (IPA):Propylene glycol (PG) (70:30% v/v) solvent mixture was further increased by lemon oil. The flux of flurbiprofen through ethylene vinyl acetate microporous membrane was evaluated. The membrane altered the flux of flurbiprofen significantly. The reservoir type of transdermal patch was fabricated using flurbiprofen viscous system, ethylene vinyl acetate membrane, and backing film. Histological investigations were done on rat skin samples treated with solvent systems with or without penetration enhancer for 24 hr. No skin irritation was seen. Lemon oil produced more pronounced change in stratum corneum and the epidermis as compared with the control groups. The pharmacokinetics of flurbiprofen in albino rats following application of a transdermal patch for 24 hr was evaluated. The maximum plasma concentration (C(max)) and AUC(0-alpha) of the patch formulation was 1.7 and 1.6 times, increased respectively as compared with the control patch formulation. Quantity of the drug accumulated in the excised skin to which test patch formulation was applied was more than the one to which control patch formulation was applied. Anti-inflammatory effect in the Carrageenin-induced paw edema in rat was significantly higher than the control patch formulation.

Administration, Cutaneous↗

PubMedDate not supplied

Sensation seeking and drinking game participation in heavy-drinking college students.

Previous research has identified differences between heavy-drinking students who play drinking games and those who do not. Johnson, Wendel, and Hamilton (1998) suggested that heavy-drinking players may correspond to Cloninger's (1987) Type II alcoholic and that heavy-drinking nonplayers resemble Type I. The current study predicted that (a) sensation seeking would be associated with greater frequency of play and greater frequency of negative consequences from play and that (b) heavy-drinking students who play drinking games would be higher in sensation seeking than heavy-drinking students who do not play. A sample of 172 female and 84 male college students completed the Sensation Seeking Scale Form V, questions about quantity and frequency of alcohol consumption, and questions regarding drinking game participation. Higher levels of sensation seeking predicted greater frequency of play even after controlling for overall quantity and frequency of consumption. Sensation seeking was also related to specific motives for play. Men who were higher in sensation seeking experienced more negative alcohol-related consequences as a result of play. In women, but not in men. heavy-drinking players were higher in sensation seeking than heavy-nondrinking nonplayers. The results of the current study do not clearly support Cloninger's model, but they are consistent with other research concerning the role of sensation seeking and risk taking in contributing to negative alcohol-related consequences. Personality style likely interacts with social norms and contextual factors in influencing drinking game participation and consequences of play.

Adolescent↗

PubMed2006

Stimulation of expression of the intestinal glutamine transporter ATB0 in tumor-bearing rats.

BACKGROUND: Glutamine supplementation ameliorates host catabolic response in tumor bearing states. The purpose of this in vivo study was to investigate intestinal glutamine transport and expression of glutamine transporter ATB(0) in methyl-cholanthrene (MCA)-sarcoma bearing rats. METHODS: Fisher-344 rats underwent subcutaneous flank implantation of MCA-sarcoma cells (saline as control) and were pair-fed an equal quantity of chow as controls, to account for tumor-induced anorexia, until tumors reached 10 or 20% body weight. Intestinal mucosal brush border membrane [3H]-Glutamine transport was measured. Glutamine transporter ATB(0) mRNA and protein levels were measured by real-time PCR and western blot techniques, respectively. RESULTS: Glutamine transport activity across the intestinal brush border membrane (BBM) was 3.7-fold higher in tumor-bearing rats (TBR) than in controls (TBR 153 +/- 22.6 vs. Control 41.9 +/- 9.7 pmol/mg protein/10s, P < .01). Transporter ATB(0) mRNA levels were 1.4-fold higher in tumor-bearing rats (Relative value TBR .61 +/- .12 vs. Control .43 +/- .1, P < .05). A 1.4-fold increase in transporter ATB(0) protein levels was observed in the tumor-bearing rats (Relative value TBR .52 +/- .07 vs. Control .37 +/- .04, P < .05). Circulating aortic plasma glutamine levels were 1.3-fold higher in tumor bearing rats ([Glutamine] = .63 +/- .02 Control vs. [Glutamine] = .74 +/- .01 mmol/l TBR, P < .0001). Portal venous plasma glutamine levels were also higher in tumor bearing rats ([Glutamine] = .47 +/- .01 Control vs. [Glutamine] = .60 +/- .02 mmol/l TBR, P < .0001). CONCLUSION: Intestinal brush border membrane glutamine transport activity, transporter ATB(0) mRNA and protein levels are up-regulate in tumor-bearing rats.

Animals↗

PubMed2001

Levels of ACC and related compounds in exudate and extracts of canola seeds treated with ACC deaminase-containing plant growth-promoting bacteria.

It was previously proposed that plant growth-promoting bacteria that possess 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase could utilize ACC that is present in the exudate of germinating canola seeds. The uptake and cleavage of ACC by these bacteria would lower the level of ACC, and thus ethylene within the plant, and reduce the extent of its inhibition on root elongation. To test part of the above mentioned model, ACC levels were monitored in canola seed tissues and exudate during germination. Lower amounts of ACC were present in the exudate and tissues of seeds treated with the plant growth-promoting bacterium Enterobacter cloacae CAL3, than in control seeds treated with MgSO4. The ACC-related compounds, alpha- and gamma-aminobutyric acids, both known to stimulate ethylene production, were also measured in the canola seed exudate and tissues. Approximately the same levels of alpha-aminobutyric acid were present in the exudates of the bacterium-treated seeds and the control seeds, but the amount of alpha-aminobutyric acid was lower in the tissues of the bacterium-treated seeds than in the control seeds. Smaller quantities of gamma-aminobutyric acid were seen in both the exudate and tissues of the E. cloacae CAL3-treated seeds than in the control seeds.

Amino Acids, Cyclic↗

PubMed2005

[Isolation and culture of mouse marrow mesenchymal stem cells (MSCs) and biological characteristics of MSCs cultured in conditions for spermatogonia in vitro].

OBJECTIVE: To isolate, culture and purify mouse bone marrow mesenchymal stem cells (MSCs) and observe the main biological characteristics of MSCs cultured in conditions for spermatogonia in vitro. METHODS: The tibias and femurs were dissected from 5 - 6-week old mice and the marrow in the tibias and femurs was flushed out with medium. MSCs were isolated, cultured, purified in vitro by Percoll density gradient centrifugation combined with adherent method and identified by dynamic observation of stem cell characteristics by transmission electron microscope, HE staining, and immunohistochemical detection of cell markers. The quantities of such cytokines as IL-6, IL-8, G-CSF and SCF in culture liquid with MSCs were measured by ELISA, and compared with those of the control group. MSCs of the third generation were divided into two groups to be induced and cultured. MSCs of the control group were cultured with basal medium, while those of the experimental group with conditional medium. The results were analysed by microscopic observation, HE staining and immunohistochemical methods. RESULTS: Pure MSCs were obtained. The cultured cells, with stem cell characteristics, shuttle-shaped at HE staining, immature under the transmission electron microscope and CD44 and CD90 positive by immunohistochemical detection, could be identified as MSCs. Compared with the control group, the quantities of IL-6, IL-8, G-CSF and SCF in the experimental group increased significantly (P < 0.05). The shapes of MSCs changed and immunohistochemical staining for CD27, CD119 and Oct-4 was positive in the experimental group, but both were just the opposite in the control group. CONCLUSION: Pure MSCs can be obtained by Percoll density gradient centrifugation combined with adherent method and identified by dynamically observing stem cell characteristics, HE staining, observation under the transmission electron microscope and immunohistochemical detection of cell markers. MSCs can secrete cytokines such as IL-6, IL-8, G-CSF, SCF, and so on. MSCs cultured in conditions for spermatogonia may show some biological characteristics of spermatogonia.

Animals↗

PubMed1996

Effects of in utero cocaine exposure on the expression of mRNAS encoding the dopamine transporter and the D1, D2 and D5 dopamine receptor subtypes in fetal rhesus monkey.

The effects of in utero cocaine exposure on the development of the mRNAs encoding the dopamine transporter (DAT) and the D1, D2 and D5 dopamine receptor subtypes were determined in fetal monkey brains at day 45 and day 60 of gestation. Pregnant monkeys were treated with cocaine 3 mg/kg or saline i.m., four times a day from day 18 of gestation until the pregnancy was terminated at day 45 or day 60. The fetal brains were dissected, and tissue RNA extracted and quantified using ribonuclease protection assay analysis. In day 45 fetal monkeys, dopamine D1 and D2 receptor subtype mRNAs and DAT mRNA were found in low quantities both in control and cocaine-treated subjects. In day 60 fetal monkeys, D1 receptor mRNA levels were highest in the frontal cortex/striatal area, and low to moderate quantities were found in diencephalic and mesencephalic fetal brain regions. Dopamine D2 receptor mRNA levels were highest in the frontal cortex/striatal area, diencephalon and the midbrain, moderate in the brainstem and low in the caudal temporal lobe and surrounding cortical areas. Dopamine D5 receptor mRNA was expressed in low quantities throughout the day 60 fetal monkey brain, whereas DAT mRNA was found in the midbrain only. In utero cocaine exposure caused a significant increase in dopamine D1, D2 and D5 receptor subtype mRNAs in the frontal cortex/striatal area of day 60 fetal monkeys. These results support the hypothesis that dopamine synthesis and release may be reduced in cocaine-treated fetuses, which results in dopamine receptor up-regulation.

Animals↗

PubMed1997

An advanced demultiplexing system for physiological stimulation.

A CMOS very large scale integration (VLSI) chip has been designed and built to implement a scheme developed for multiplexing/demultiplexing the signals required to operate an intracortical stimulating electrode array. Because the use of radio telemetry in a proposed system utilizing this chip may impose limits upon the rate of data transmission to the chip, the scheme described herein was used to reduce the amount of digital information which must be sent to control a large quantity (up to several hundred) of stimulating electrodes. By incorporating multiple current sources on chip, many channels may be stimulated simultaneously. By incorporating on-chip timers, control over pulse timing is assigned to the chip, reducing by up to fourfold the amount of control data which must be sent. By incorporating on-chip RAM, information associated with the desired stimulus amplitude and pulse timing can be stored on chip. In this manner, it is necessary to send control information to the chip only when the information changes, rather than at the stimulus repeat rate for each channel. This further reduces the data rate by a factor of five to ten times or more. The architecture described here, implemented as an eight-channel stimulator, is scalable to a 625-channel stimulator while keeping data transmission rates under 2 Mbps.

Analog-Digital Conversion↗

PubMed1994

Insulin sensitivity and insulin clearance in cystic fibrosis patients with normal and diabetic glucose tolerance.

OBJECTIVE: We studied glucose metabolism and insulin kinetics in cystic fibrosis patients with diabetic and normal glucose tolerance. DESIGN: Measurements of blood glucose and serum free insulin concentrations during hyperinsulinaemic normoglycaemic clamp and post-clamp insulin decay, followed by the calculation of insulin sensitivity (M-value and M/I ratio), insulin clearance rate, serum half-life and apparent distribution space for insulin. SUBJECTS: Cystic fibrosis patients, age range 20-29 years, with diabetes mellitus (n = 10) and normal glucose tolerance (n = 10), and 10 age-matched control subjects. RESULTS: During the glucose clamp, diabetic cystic fibrosis patients needed less glucose than cystic fibrosis patients with normal glucose tolerance and control subjects (M-value), and steady-state serum insulin concentrations were lower in cystic fibrosis patients with diabetic and normal glucose tolerance than in control subjects. The quantity of glucose metabolized per unit of serum insulin concentration (M/I ratio) was similar in the three study groups (median approximately 145 (mumol/kg/min)/(nmol/l); range 70-252). Insulin clearance rates were higher in cystic fibrosis patients with diabetic (24.4 (19.3-29.9) ml/kg/min) and normal (22.6 (14.9-28.4) ml/kg/min) glucose tolerance than in control subjects (17.5 (15.9-24.2) ml/kg/min). Although insulin clearance rates were inversely related to body mass index (R(S) = -0.59, P < 0.001), the higher insulin clearance rates in CF patients cannot be accounted for solely by differences in body mass index since the insulin clearance rates were similarly increased in patients with body mass index above and below 20 kg/m2 (22.7 (14.9-28.4) and 24.4 (19.3-29.9) ml/kg/min, respectively). Serum half-lives for insulin were shorter in cystic fibrosis patients (approximately 4.3 (3.2-7.2) min) than in control subjects (5.9 (3.8-12.5) min), whereas the apparent distribution spaces for insulin were similar in the three study groups (approximately 150 (88-391) ml/kg). CONCLUSIONS: Insulin sensitivity, calculated as the quantity of glucose metabolized per kg body weight per unit of serum insulin concentration, is normal in cystic fibrosis patients with normal glucose tolerance and with well controlled diabetes mellitus. The insulin clearance rate is increased in cystic fibrosis patients with diabetic and normal glucose tolerance, owing to a shorter serum half-life of insulin, whereas the apparent distribution space for insulin is normal.

Adult↗

PubMed2004

Granulocyte-macrophage colony-stimulating factor (GM-CSF) controls the proliferation and differentiation of mouse epidermal melanocytes from pigmented spots induced by ultraviolet radiation B.

Repeated exposure of ultraviolet radiation B (UVB) on the dorsal skin of hairless mice induces the development of pigmented spots long after its cessation. The proliferation and differentiation of epidermal melanocytes in UVB-induced pigmented spots are greatly increased, and those effects are regulated by keratinocytes rather than by melanocytes. However, it remains to be resolved what factor(s) derived from keratinocytes are involved in regulating the proliferation and differentiation of epidermal melanocytes. In this study, primary melanoblasts (c. 80%) and melanocytes (c. 20%) derived from epidermal cell suspensions of mouse skin were cultured in a basic fibroblast growth factor-free medium supplemented with granulocyte-macrophage colony-stimulating factor (GM-CSF). GM-CSF induced the proliferation and differentiation of melanocytes in those keratinocyte-depleted cultures. Moreover, an antibody to GM-CSF inhibited the proliferation of melanoblasts and melanocytes from epidermal cell suspensions derived from the pigmented spots of UV-irradiated mice, but not from control mice. Further, the GM-CSF antibody inhibited the proliferation and differentiation of melanocytes co-cultured with keratinocytes derived from UV-irradiated mice, but not from control mice. The quantity of GM-CSF secreted from keratinocytes derived from the pigmented spots of UV-irradiated mice was much greater than that secreted from keratinocytes derived from control mice. Moreover, immunohistochemistry revealed the expression of GM-CSF in keratinocytes derived from the pigmented spots of skin in UV-irradiated mice, but not from normal skin in control mice. These results suggest that GM-CSF is one of the keratinocyte-derived factors involved in regulating the proliferation and differentiation of mouse epidermal melanocytes from UVB-induced pigmented spots.

Animals↗

PubMed1993

[Effectiveness of relaxation groups in patients with chronic respiratory tract diseases].

In the long-term treatment of patients with chronic respiratory diseases, patient education contributes significantly towards improving the effectiveness of conventional drugs in the treatment of asthma-specific complaints and anxiety, as well as playing a role in improved disease coping. The aim of this study was to verify whether relaxation training programs undertaken subsequent to patient education may have an additional effect with regard to both medical and psychological variables. Relaxation training encompasses the basic exercises of autogenics, as well as exercises of functional relaxation. 49 patients participated in the relaxation group (22 male, 27 female). The mean age was 50.5 +/- 16.5 years. The control group used was made up of 37 patients with chronic respiratory diseases (17 male, 20 female) who had received asthma education, but no further therapeutic intervention. Prior to and immediately after the relaxation training, the following investigations were undertaken: lung function, patient diary, Spielberger anxiety scale, Giessen list of complaints (modified and augmented) and Ziegler coping questionnaire. The linear rating scale model was used for measuring changes. The following significant changes were observed in the relaxation group as compared with the control group: decrease of trait fear, alleviation of asthma-specific complaints and asthma attacks, decrease in sleep disturbances and in morning coughing urge, reduction in the required quantities of controlled-dosage aerosol, and a modified attitude toward the disease in the sense of an improved subjective coping competence.(ABSTRACT TRUNCATED AT 250 WORDS)

Adaptation, Psychological↗

PubMed2004

In vitro tobramycin elution analysis from a novel beta-tricalcium phosphate-silicate-xerogel biodegradable drug-delivery system.

This in vitro research analyzed local tobramycin elution characteristics from a novel, biodegradable drug delivery system, consisting of a beta-TCP bone substitute, VITOSS trade mark, encapsulated with silicate xerogel prepared by the sol-gel process. Tobramycin elution from silicate-xerogel-encapsulated VITOSS was compared directly with non-silicate-xerogel-encapsulated VITOSS to assess whether xerogels are effective in delivering greater tobramycin quantities in a controllable, sustained manner crucial for microbial inhibition. Tobramycin elution characteristics indicate an initial release maximum during the first 24 h that diminishes gradually several days after impregnation. The copious tobramycin quantity eluted from the VITOSS/silicate-xerogel systems is attributed to various factors: the intrinsic ultraporosity and hydrophilicity of VITOSS, the ability of tobramycin to completely dissolve in aqueous media, tobramycin complexation with highly polar SO(4) (2-) salts that further assist dissolution, and ionic exchanges between VITOSS and the environment. Silicate-xerogel-encapsulated VITOSS eluted 60.65 and 61.31% of impregnated tobramycin, whereas non-silicate-xerogel-encapsulated VITOSS eluted approximately one-third less impregnated tobramycin, at 21.53 and 23.60%. These results suggest that silicate xerogel optimizes tobramycin elution because of its apparent biodegradability. This mechanism occurs through xerogel superficial acidic sites undergoing exchanges with various ions present in the leaching buffer. Tobramycin elution kinetics were evaluated, and demonstrate that first-order elution rate constants are considerably less when silicate xerogels are employed, following a more uniform exponential decay-type mechanism, thus bolstering controlled release. Overall, tobramycin elution rates adhere to linear-type Higuchi release profiles. Elution rate constants are initially first order, and taper into zero-order elution kinetics in the latter stages of release. Because VITOSS and silicate xerogel are completely biodegradable, essentially all impregnated tobramycin will be delivered to the surgical site after implantation.

Anti-Bacterial Agents↗

PubMed1991

Heterochromatic variability in children with acute lymphoblastic leukemia.

An analysis of the C-segment variability of chromosomes 1, 9, and 16 was carried out in 38 children with ALL, and 90 control subjects. When studying location variants, no differences were found between group of patients and the normal controls. A larger quantity of structural heterochromatin was, however, observed on chromosomes 1, 9, and 16, and a higher frequency of homologous chromosomes heteromorphism in children with ALL when compared with the control group.

Child↗