Biomedical subjects

C C Liu

Publications and source records attributed to C C Liu.

At least 163 records · Page 9Linked to original sources

PubMed1994

Comparison of physical properties of light-curing and self-curing dental impression materials.

A light-curing polyether urethane dimethacrylate impression material was recently developed. Its polymerization reaction is activated by intensified visible light; therefore, the on-demand set allows operators to work at their own pace. Furthermore, its constant viscosity provides a constant flow rate at the critical stages of taking impressions. The purposes of this study were to evaluate the physical properties and accuracy of this light-curing impression material and to compare it with those of self-curing impression materials currently used in our dental clinic. Physical properties such as strain in compression, compression set, dimensional stability, and tear strength of the impression materials were measured according to test methods stipulated in ADA Specification No. 19 for elastomeric impression materials. The template-coping method developed by Lewinstein and Craig was used to evaluate the accuracy of the impression materials. It was found that the strain in compression of the polyether urethane dimethacrylate was higher than that of the condensation silicones, but lower than that of the addition silicones. The compression set of the condensation silicones was more than that of the polyether urethane dimethacrylate, but much less than that of the polysulfides. The dimensional stability showed that all of the impression materials, except the polyether urethane dimethacrylate, had a negative dimensional change 24 hours after mixing. The sequence is: polysulfide < condensation silicone < addition silicone. The expansion rate of the light-curing material was measured under 0.07% one day after curing. The polyether urethane dimethacrylate had extraordinary tear resistance compared to the other impression materials.(ABSTRACT TRUNCATED AT 250 WORDS)

Biomechanical Phenomena↗

PubMed1994

Precipitation profile of the intravenous induction agents.

To investigate the formation of precipitation between various intravenous agents, we cross-matched the anesthetic agents commonly used in the induction phase. Thiopentone and thiamylal precipitated in combination with non-depolarizing muscle relaxants, lidocaine, morphine, and meperidine. Ketamine and etomidate were naive to these agents. Crystalloidal solutions, such as lactated Ringer, normal saline, and dextrose solution did not contribute to the formation of precipitate. In conclusion, our study indicates that intravenous line must be irrigated before and after thiopentone and/or thiamylal. In order to prevent precipitate formation, mixtures of various drugs should be avoided until in vitro assay is done.

Anesthesia, Intravenous↗

PubMed1994

Recovery from propofol anesthesia: a quantitative electroencephalographic analysis.

Four numerical descriptors (median frequency, spectral edge frequency-95%, total power, and delta-ratio) derived from the computer-processed electroencephalogram (Neurometrics Lifescan) were analyzed for their ability to predict imminent arousal from total intravenous anesthesia with propofol. Fifteen patients undergoing minor surgical procedures without intubation were enrolled in the study. Arousal was defined as eye opening in response to verbal stimuli. During emergence from propofol, there were no significant changes among the descriptors except the delta-ratio. Significant change of delta-ratio occurred 210 seconds before patients' arousal and thereafter. An increase of delta-ratio value indicates that patients shifted from anesthetic to arousal state. It is concluded that the degree of delta-ratio change may be used for predicting patients' arousal from propofol anesthesia.

Adult↗

PubMed1994

Propofol modifies recovery from isoflurane-nitrous oxide anesthesia.

A randomized, prospective study was performed to evaluate the hemodynamic changes and recovery characteristics in 60 ASA physical status class I-II unpremedicated patients undergoing gynecological laparotomies with either isoflurane anesthesia only (ISO group) or isoflurane anesthesia followed by propofol infusion (ISO-PRO group). All patients received isoflurane 0.5-1.5% and nitrous oxide (N2O) 66% in oxygen after tracheal intubation. ISO-PRO group (n = 30) received 6 mg kg-1 hr-1 propofol infusion in substitution for isoflurane 25 minutes before the end of surgery. Propofol in ISO-PRO group and isoflurane in ISO group (n = 30) were discontinued 5 minutes before the end of surgery. In both groups, N2O was administered throughout the operation until skin was closed. Hemodynamic measurements were similar between the two groups except at extubation when heart rate and blood pressure were lower in ISO-PRO group. The maximal blood pressure was also lower in ISO-PRO group. In ISO-PRO group, the time required to responsiveness to verbal commands and to orientation were significantly shorter. ISO-PRO group had better Steward's score on arrival at the recovery room and was earlier to get a full score of six. The two groups experienced similar rates of emesis and excitement either two hours or 24 hours postoperatively. We conclude that in relatively long intra-abdominal operations, replacement of isoflurane by propofol infusion 25 minutes before the end of surgery may provide stable maintenance of anesthesia and a faster recovery.

Adult↗

PubMed1994

The effect of low dose propofol for prevention of nausea and vomiting during spinal anesthesia for cesarean section.

In order to investigate the possible antiemetic property of propofol at subhypnotic dosage, fifty patients scheduled for elective cesarean section under spinal anesthesia were accepted into the study. Patients were randomly given intravenous propofol 10 mg (group I) or 1 ml intralipid (group II) after delivery of the infant. Overall incidence of nausea (24% in group I and 40% in group II) and vomiting (16% in group I and 20% in group II) were not statistically different in the two groups. However, onset time to the appearance of nausea and vomiting were longer in group I (14 +/- 5.8 min vs 5.4 +/- 3.6 min). In conclusion, low dose propofol (10 mg) administered during spinal anesthesia for cesarean section failed to reduce the incidence of emesis.

Adult↗

PubMed1994

Hyperbilirubinemia after cardiac operation. Incidence, risk factors, and clinical significance.

Three hundred and two consecutive patients who had undergone cardiac operation for various cardiac lesions were studied prospectively to evaluate the incidence, risk factors, and the associated mortality of postoperative hyperbilirubinemia after cardiopulmonary bypass. Concentrations of the serum total (conjugated and unconjugated) bilirubin, alanine aminotransferase, aspartate aminotransferase, lactate dehydrogenase, alkaline phosphatase, albumin, globulin, and serum haptoglobin were measured before the operation and again on the first, second, and seventh postoperative days. Postoperative hyperbilirubinemia was defined as occurrence of a serum total bilirubin concentration of more than 3 mg/dl in any measurement during the postoperative period. Logistic regression was done to identify possible risk factors for postoperative hyperbilirubinemia. Overall incidence of postoperative hyperbilirubinemia was 35.1%; the incidence of postoperative hyperbilirubinemia was higher in patients whose valves were replaced with mechanical prostheses than in those without prostheses (p < 0.00001). In patients with postoperative hyperbilirubinemia, 70% of the increase of total bilirubin on the first postoperative day came about from an increase in unconjugated bilirubin. Serum haptoglobin decreased significantly at the same time (p < 0.01). Development of the postoperative hyperbilirubinemia was associated with a higher mortality (5.6% versus 0.5%, p < 0.01) and higher frequency of use of intraaortic balloon counterpulsation, especially for patients in whom the highest postoperative total bilirubin occurred after the first 2 days. The numbers of valves replaced, preoperative right atrial pressure, and preoperative total bilirubin concentration are the significant risk factors that, in combination, correctly predict the occurrence of postoperative hyperbilirubinemia in 80% of the patients. We concluded that postoperative hyperbilirubinemia results mainly from an increase in unconjugated bilirubin and is associated with higher mortality, especially for patients in whom highest postoperative total bilirubin occurred late after operation. Patients with the higher preoperative right atrial pressure and total bilirubin level who then underwent multiple valve replacement procedures are at greater risk for development of postoperative hyperbilirubinemia.

Cardiac Surgical Procedures↗

PubMed1994

Heart rate variability--a useful non-invasive tool in anesthesia.

Fluctuations in heart rate (HR) and arterial blood pressure occurring at respiratory and lower frequencies have long been recognized. However, their significance remained obscure until the monitoring of fetal heart-rate variability (HRV) was appreciated. Recent studies suggest that HRV may reflect the sympatho-vagal interactions that modulate cardiovascular function. Analysis of HRV can provide a noninvasive measure of central autonomic outflow and autonomic reflex functions. A mathematical and signal-processing technique called power spectral analysis (PSA) has been used extensively to quantify HRV. Several frequencies of HR oscillations can be quantified: the low-frequency peak (LFP 0-0.04 Hz), the mid-frequency peak (MFP 0.05-0.15 Hz) and the high-frequency peak (HFP 0.15-0.4 Hz). In this review article, the physiological origins of these HR fluctuations are described and the changes of HRV by different pathophysiological states are also discussed. In conclusion, spectral analysis of HRV may provide important insights regarding the influence of anesthesia on cardiovascular neural control and anesthetic depth and the monitoring may be developed as a very useful non-invasive tool for modern anesthesia in the near future.

Anesthesia↗

PubMed1993

Identification of a putative tyrosine-O-sulphate (TyrS) receptor possibly functioning in the biosynthetic transport of tyrosine-sulphated proteins in Madin-Darby canine kidney cells.

By employing an affinity-gel fractionation technique coupled to Western-blot analysis, we have identified a 175 kDa tyrosine-O-sulphate (TyrS)-binding protein present in Madin-Darby canine kidney (MDCK) cells. The binding of this TyrS-binding protein to TyrS covalently bonded to Sepharose gel was found to be pH-dependent, being strong from pH 8.0 down to pH 6.5 and increasingly weak at pH 6.0 and below. Results obtained from Triton X-114 temperature-induced phase separation and sodium carbonate buffer (pH 11) extraction experiments indicated that the TyrS-binding protein is an integral membrane protein. This 175 kDa TyrS-binding protein was found to be present in association with a major tyrosine-sulphated protein, the apically secreted 80 kDa glycoprotein (gp 80), in cell lysate prepared from MDCK cells maintained under normal growth conditions. When the cell lysate used was prepared from MDCK cells pretreated with 20 mM sodium chlorate, a metabolic sulphation inhibitor, the complex formed between the two proteins could no longer be detected, indicating that the binding of the TyrS-binding protein is through the TyrS residue(s) of gp 80. Both cell-surface biotinylation and cell-surface trypsinization studies demonstrated the predominantly, if not exclusively, intracellular location of the TyrS-binding protein. Furthermore, radioactive pulse-chase experiments revealed that the newly synthesized radiolabelled fibronectin and gp 80 were present in complexes with the TyrS-binding protein in MDCK cells pulse-labelled with [35S]methionine or [35S]sulphate. Exogenous [35S]methionine-labelled gp 80 added to the medium, on the other hand, was not found to be present in association with the TyrS-binding protein in MDCK cells over a 2-h time course. These results strongly suggested the identity of the 175 kDa TyrS-binding protein as a putative 'TyrS receptor', possibly functioning in the biosynthetic transport of tyrosine-sulphated proteins in MDCK cells.

Animals↗

PubMed1993

Modulation by adjuvants and carriers of the immunogenicity in xenogeneic hosts of mouse anti-idiotypic monoclonal antibody MK2-23, an internal image of human high molecular weight-melanoma associated antigen.

The mouse anti-idiotypic monoclonal antibody (mAb) MK2-23 recognizes an idiotope in the antigen-combining site of the immunizing anti-human high-molecular-weight melanoma-associated antigen (HMW-MAA) mAb 763.74. Administration with an adjuvant of mAb MK2-23 conjugated to a carrier has been shown to induce anti-HMW-MAA antibodies both in syngeneic hosts and in patients with malignant melanoma. Adjuvant and carrier are required for the induction of anti-HMW-MAA immunity in BALB/c mice immunized with mAb MK2-23. Whether both adjuvant and carrier are required also in patients with malignant melanoma is not known and cannot be deduced from results obtained in a syngeneic animal model system. Therefore the present study has evaluated for the first time the effect of a carrier and an adjuvant on the immunogenicity of mAb MK2-23 in a xenogeneic host. Rabbits were selected for this purpose, since they have a constitutive expression of HMW-MAA in their normal tissues with a distribution similar to that in humans. The combined use of an adjuvant and a carrier enhances the immunogenicity of mAb MK2-23 in rabbits markedly more than each of them individually. Specifically, all the rabbits immunized with mAb MK2-23 conjugated to keyhole limpet hemocyanin (KLH) and mixed with Freund's adjuvant (FA) produced antibodies which were shown with serological and immunochemical assays to be specific for HMW-MAA and to be both IgG and IgM. In contrast anti-HMW-MAA antibodies were detected in only one of the 3 rabbits immunized with mAb MK2-23 mixed with FA and were not detected in the rabbits immunized with mAb MK2-23 conjugated to KLH or with mAb MK2-23 without KLH and FA. These results indicate that active specific immunotherapy with mAb MK2-23 in patients with malignant melanoma is likely to benefit from the use of a carrier and an adjuvant, provide additional evidence that mAb MK2-23 bears the internal image of HMW-MAA, and suggest that the immune response elicited by mAb MK2-23 is T-cell dependent.

Adjuvants, Immunologic↗

PubMed1993

Additive effect of treadmill exercise and 17 beta-estradiol replacement on prevention of tibial bone loss in adult ovariectomized rat.

The effects of 17 beta-estradiol (E2) and treadmill exercise on tibial bone mass, tibial uptake of 45Ca, and proximal tibia osteoblast and osteoclast cell number were determined in adult ovariectomized rats. Female rats aged 10 months were ovariectomized and divided into five groups: (1) sham-operated; (2) ovariectomized; (3) ovariectomized, given 10 micrograms E2 biweekly; (4) ovariectomized, trained to exercise on a treadmill daily; and (5) ovariectomized, given E2 and exercised. E2 and/or exercise interventions were started 2 months following surgery and continued for 4 months. The calcium content of the tibial metaphysis and diaphysis and the proximal cancellous bone (BV/TV) were lower in the ovariectomized than in the sham-operated controls 6 months after ovariectomy. This lower bone content was associated with a greater bone uptake of 45Ca and a greater number of osteoblasts and osteoclasts in the proximal tibia compared to the control rats. The metaphyseal calcium content was higher and the 45Ca uptake and osteoblast and osteoclast number were lower in the E2-treated rats than in the nontreated rats. In the exercised group, higher diaphyseal calcium content and proximal cancellous bone were associated with lower bone resorption parameters without a significant effect on bone formation. This study demonstrates that E2 primarily influences tibial cancellous bone of the ovariectomized rat and a positive adaptation to exercise occurs in both cancellous and cortical bone. Under estrogen deficiency, E2 replacement suppresses increased bone formation and resorption; exercise suppresses mainly bone resorption. The effects of E2 replacement and exercise training are independent and additive.

Animals↗

PubMed1993

GABAA receptor function in the gamma-hydroxybutyrate model of generalized absence seizures.

gamma-Hydroxybutyric acid (GHB) produces absence-like seizures when given to animals. One of the distinguishing characteristics of experimental generalized absence seizures is that they are exacerbated by GABAA agonists. Therefore, the hypothesis that GHB-induced absence seizures result from an interaction between GHB and the GABAA receptor complex was tested. The effect of GHB on the function of various components of the GABAA receptor complex in the cortex of the rat, was determined in a series of in vitro experiments. Similar studies were carried out at various times following systemic administration of the prodrug of GHB, gamma-butyrolactone (GBL) and changes in the GABAA receptor were correlated with electrographic and behavioral changes. gamma-Hydroxybutyric acid had no effect on the binding of [3H]muscimol, [3H]flunitrazepam and [35S]t-butylbicyclophosphorothionate (TBPS) or on the uptake of 36Cl- into synaptoneurosomes in the in vitro studies. Nor were changes observed after the administration of GBL before the onset of GHB-induced absence seizures. However, at the onset of GHB-induced spike wave discharge, there was a significant (P < 0.04) decrease in the binding of [35S]TBPS, associated with a significant decrease in muscimol-stimulated uptake of 36Cl- with no other biochemical change. One minute after onset of GHB-induced absence seizure, a significant (P < 0.05) increase in the binding of [3H]muscimol was noted. Ten minutes later the decrease in muscimol-stimulated uptake of 36Cl- had normalized, while the changes in binding of [3H]muscimol and [35S]TBPS persisted. Because GABAA function remained unchanged in the in vitro studies, as well as prior to the onset of GHB-induced absence seizures in the in vivo experiments, these studies do not support the hypothesis that GHB interacts directly with the GABAA receptor complex to produce absence-like seizures.

Aminocaproates↗

PubMed1993

Use of monoclonal antibodies to isolate and characterize Cyn d I, the major allergen of Bermuda grass pollen.

BACKGROUND: Cyn d I has been found to be the major allergen of Bermuda grass (Cynodon dactylon) pollen, but its exact nature remains to be clarified. METHODS: Cyn d I, the major allergen of Bermuda grass (Cynodon dactylon) pollen, was purified by monoclonal antibody (MoAb) affinity chromatography, and its biochemical and immunologic properties were characterized. Anti-Cyn d I MoAb 4-37, which recognizes all of the isoallergens of Cyn d I, was chosen as the immunosorbent. RESULTS: The purified protein has an amino acid composition similar to that of the group I allergens of other grass pollens. It appears as a single 34 kd band or as a mixture of 34 and 29 kd polypeptides in sodium dodecylsulfate-polyacrylamide gel electrophoresis analysis. The hydrophobicity of these two polypeptides is similar because they have the same retention time on a C18 reverse-phase column when a trifluoroacetic acid/H2O/CH3CN buffer system is used. The N-terminal amino acid sequence of the 34 kd component has a 60% homology with residues of 1-25 of Lol p I, whereas that of the 29 kd component has a 68% homology with residues 31-68 of Lol p I. In addition, this 29 kd polypeptide can be recognized by another anti-Cyn d I MoAb 1-61. CONCLUSIONS: These results suggest that the 29 kd component is derived from Cyn d I. In spite of the similarity in the amino acid composition between Cyn d I and group I allergens of other grass pollens, none of our four anti-Cyn d I MoAbs cross-reacted with 10 other grass pollens tested, including ryegrass pollen. Despite biochemical similarity with other group I allergens, the B-cell epitopes on Cyn d I are different from those on other grass pollens.

Allergens↗

PubMed1993

The effect of repeated stretching on the force decay and compliance of vulcanized cis-polyisoprene orthodontic elastics.

Compliance measurements, used in the past to measure the viscoelastic properties of dental impression materials, were used to assess these properties in vulcanized cis-polyisoprene orthodontic elastics, and the results were compared with traditional force decay measurements. Both methods were also used to evaluate the effect of repeated stretching on these elastics. Compliance measurements successfully characterized the viscoelastic behavior of the elastics, and the results agreed with force decay measurements. Repeated stretching significantly reduced the force and the compliance of the elastics. There was no statistical difference in the force or compliance measurements after the elastics were stretched more than 200 times. Stretching for 1000 cycles of 400% extension reduced elastic force by approximately 12%.

Analysis of Variance↗

PubMed1993

The differences in growth of cerebellar vermis between appropriate-for-gestational-age and small-for-gestational-age newborns.

To determine whether there is any difference in the growth of the cerebellar vermis between appropriate-for-gestational-age (AGA) and small-for-gestational-age (SGA) infants during fetal life, the central vermian area (Cva) of the cerebellum and its anterior-posterior distance (Vap) and superior-inferior distance (Vsi) were measured by midsagittal cerebral ultrasonography in 218 newborns within 24 h of birth. Patients with congenital infections and malformations were excluded. One-hundred twenty-one infants were AGA and 97 SGA. Best curve-fit of second-degree polynominal equations were found between gestational age and Cva, Vap, Vsi in both AGA and SGA neonates. Among them, Cva correlated best with gestational age in both AGA and SGA newborns. Comparing the head circumference (HC), Cva, Vap and Vsi between AGA and SGA neonates in the four gestational age subgroups (24-28, 29-33, 34-37 and 38-41 weeks), significant differences in HC were found in the 34-37 weeks (P < 0.01) and 38-41 weeks (P < 0.001) subgroups. But the significant differences in Cva and Vsi were found only in the 38-41 weeks subgroup. There is more accelerated growth in vermis from 34 to 41 weeks of gestation than that from 24 to 33 weeks. Comparing with AGA, the non-fetal cause of intrauterine growth retarded newborns demonstrate growth retardation in the cerebellar vermis only at late gestation. The cerebellar vermis measured by cranial ultrasound may serve as part of the neurological maturation assessments in newborns. Further work is needed to establish the normogram for the cerebellar vermis in newborns, and to assess the neurodevelopmental outcomes of those with an abnormal vermis.

Biometry↗

PubMed1993

Ovariectomy-induced bone loss and the hematopoietic system.

To investigate the relationship of the hematopoietic system to the loss of bone due to ovarian hormone deficiency, we examined the effects of ovariectomy and estrogen administration on the thymus, spleen and the bone marrow, and on the proliferation of marrow progenitors of osteoclasts. We also assessed the effects of daily administration of interleukin-1 receptor antagonist (IL-1ra) on bone loss due to ovarian hormone deficiency. Ovariectomy resulted in decreased cancellous bone volume, increased trabecular osteoblast and osteoclast numbers, and increased serum alkaline phosphatase levels that were prevented by 17 beta-estradiol treatment. Thymus weight, spleen weight, thymus and spleen lymphocytes, and bone marrow monocytes and lymphocytes also increased significantly following ovariectomy, and the increases were suppressed by 17 beta-estradiol. Ovariectomy, in addition, caused a 4-fold increase in the number of tartrate resistant acid phosphatase (TRAP)-positive multinucleated cells formed in cultures of marrow cells and the increase was partially inhibited by 17 beta-estradiol. IL-1ra administration did not prevent the bone loss due to ovariectomy. Our findings indicate that ovariectomy-induced bone loss in the rat is accompanied by marked changes in the hematopoietic system, and that these changes are modulated by estrogen administration. In spite of the negative finding with IL-1ra, the nature of the involvement of the hematopoietic system in the pathogenesis of bone loss due to ovarian hormone deficiency merits continued exploration.

Acid Phosphatase↗

PubMed1993

In vivo effects of transforming growth factor-beta 2 in ovariectomized rats.

In vitro studies indicate that transforming growth factor-beta (TGF-beta) has a role in the regulation of bone cell activities. However, little is known about the effects of TGF-beta on bone when it is administered systemically. This study was undertaken to evaluate the in vivo effects of TGF-beta 2 on bone and marrow cells in the ovariectomized rat bone loss model. Female Sprague-Dawley rats, aged 95 days, were divided into 4 groups. Group 1 was sham operated; groups 2-4 were ovariectomized. Groups 3 and 4 received daily injections of 10 micrograms and 50 micrograms of TGF-beta 2/kg body weight, respectively. Groups 1 and 2 received the solvent vehicle. All animals were sacrificed after 35 days. Ovariectomy caused a significant increase in, total mononuclear marrow cells, the number of TRAP positive multinucleated cells formed in culture of marrow cells, and the number of trabecular osteoclasts and osteoblasts. These increases were associated with loss of cancellous bone in the proximal tibia. TGF-beta 2 completely prevented the increase in the number of TRAP positive multinucleated cells, and caused a small but not statistically significant decrease in the number of trabecular osteoclasts. However, TGF-beta 2 had no significant effect on the number of total mononuclear marrow cells and on the loss of cancellous bone due to ovariectomy. We conclude that TGF-beta 2 probably plays a role in the regulation of the proliferation of osteoclast progenitors in bone marrow in vivo. Studies carried out over a longer period are required to determine whether it will modulate the increase in osteoclast and osteoblast numbers that occur in cancellous bone following ovariectomy.

Animals↗

PubMed1993

Estrogen modulates the mRNA levels for cancellous bone protein of ovariectomized rats.

This study was undertaken to examine the effects of ovariectomy and 17 beta-estradiol (E2) on the gene expression of type 1 collagen, osteocalcin and the protooncogen, c-myc, in cancellous bone. Female Sprague-Dawley rats, aged 95 days, were divided into 4 groups. Group 1 was sham operated and Groups 2-4 were ovariectomized. Groups 3 and 4 received daily injections of 160 ng and 1600 ng E2/kg body weight, respectively. Groups 1 and 2 received the solvent vehicle. All animals were sacrificed after 14 days. The femurs were dissected out and cancellous bone scraped from the distal metaphysis. RNA was isolated from the cancellous bone, immobilized on filters or size-fractionated by agarose gel electrophoresis and adsorbed on filters which were then hybridized with specific cDNA probes. Ovariectomy resulted in a significant increase in the mRNAs of type 1 collagen, osteocalcin and c-myc. The increase was suppressed in animals that received 17 beta-estradiol injections. In addition, ovariectomy caused the expected decrease in cancellous bone in the proximal tibia and increased osteoclast and osteoblast numbers. The ovariectomy-induced changes were prevented by 17 beta-estradiol administration. These findings suggest that the lack of ovarian hormones shortly after ovariectomy up-regulates and estrogen administration down-regulates the expression of important cancellous bone matrix proteins as well as the protooncogen, c-myc.

Animals↗

PubMed1993

A histomorphometric comparison of bone in young growing rats fed an elemental diet versus a chemically defined polymeric diet.

This study was designed to examine whether a synthetic elemental diet, which could be adapted for total parenteral nutrition, is capable of promoting bone growth comparable to a commercially available liquid polymeric diet. The orally fed young rat was chosen as a model of rapid bone growth. Sixteen male, Wag/Rij rats weighing 120 +/- 3 g were divided into two groups of eight rats each. One group was fed an elemental diet formulated to approximate the nutritional requirements of the rat as recommended by the National Research Council. The comparison group received a liquid polymeric diet. After 14 days there were no significant differences between groups in femur and tibia weights, cortical and medullary area, periosteal and endosteal label area, growth plate width, percent cancellous bone, bone apposition rates and osteoblasts and osteoclasts per millimeter. Both groups maintained a positive calcium and nitrogen balance. These data indicate that bone growth, structure and remodeling comparable to that seen in a polymeric-fed comparison group can be achieved in young rats when fed an oral dextrose/amino acid-based elemental solution for 2 weeks.

Animals↗