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Biomedical subjects

C McClain

Publications and source records attributed to C McClain.

At least 19 recordsLinked to original sources
PubMed1999

Evaluation of the feasibility and use of a prototype remote drug delivery capsule (RDDC) for non-invasive regional drug absorption studies in the GI tract of man and beagle dog.

PURPOSE: Evaluate a prototype Remote Drug Delivery Capsule (RDDC) for use in beagle dogs and human volunteers for non-invasive drug absorption studies in different regions of the gastrointestinal tract. METHODS: The device was dual radiolabeled and GI transit of the RDDC was monitored by gamma scintigraphy. Beagles were used initially to demonstrate the functional utility of the device where a solution of ranitidine hydrochloride (150 mg) was non-invasively delivered to the stomach, proximal small intestine and distal small intestine. A subsequent first time in human study enrolled twelve healthy male volunteers where the intended site of release was the stomach, early small bowel, distal small bowel or colon. RESULTS: Preliminary studies conducted in beagles indicated that the RDDC operated successfully and the onset of ranitidine serum levels were dependent on the time of capsule activation and site of drug release. Results from the human study showed that all twelve subjects swallowed the device with no discomfort. Mean gastric emptying of the RDDC was 1.50 +/- 1.28 h (range = 0.25 to 4.25 h), and total small intestine transit was 4.79 +/- 1.82 h (range = 2.00 to 8.25 h). The capsule was retrieved from the feces at 30.25 +/- 15.21 h (range = 14.12 to 74.25 h) and there were no reported adverse events. The prototype RDDC operated successfully in nine of the twelve human volunteers and the cause for the three failures was attributed to mechanical failure while the electronics assembly performed favorably. CONCLUSIONS: This prototype remote control capsule was shown to be well tolerated and functional to use in human volunteers as well as beagles. The application of the device coupled with gamma scintigraphy has the potential to be a valuable and rapid method to non-invasively evaluate regional drug absorption in the gastrointestinal tract under conditions that are both pharmaceutically and physiologically meaningful.

Adult↗
PubMed1997

The use of upper extremity anthropometrics in the clinical assessment of patients with amyotrophic lateral sclerosis.

We evaluated the feasibility of using upper extremity anthropometrics to monitor the clinical status of 18 patients with amyotrophic lateral sclerosis (ALS). The bone-free arm muscle area (AMA) was computed using measurement of triceps skinfold thickness and the mid-upper arm circumference according to published formulae. The AMA correlated significantly with body mass, isokinetic muscle force generation, cross-sectional muscle area on computerized tomography scanning, and pulmonary functions including forced vital capacity and maximal voluntary ventilation. Serial determinations of AMA demonstrated a decline in 10 of 13 patients over 6 months. We pilot tested the use of AMA in a clinical trial of ciliary neurotrophic factor (CNTF) in the treatment of ALS. The AMA progressively decreased by 13%, 15%, and 30% in ALS patients treated with 0 microg CNTF/kg, 15 microg CNTF/kg, and 30/microg CNTF/kg, respectively, over a 9-month treatment period. We conclude that measurement of AMA provides a simple, inexpensive method to monitor the progression of muscle atrophy in ALS patients. The technique does not require effort on the part of the patient and as such, appears to have potential utility as an outcome measure in clinical drug trials.

Adult↗
PubMed1997

Expansion of the myotonic dystrophy CTG repeat reduces expression of the flanking DMAHP gene.

Myotonic dystrophy, or dystrophia myotonica (DM), is a highly variable multisystem disease in which the classic adult-onset form displays progressive muscle wasting, cataracts, heart block, gonadal atrophy, insulin resistance and neuropsychiatric impairment. Its genetic basis is an expansion of CTG trinucleotide repeats in the DMPK protein kinase gene. Among the triplet repeat expansion disorders, DM is distinguished by the extended length of the repeat tract (5-13 kb in postmortem tissue) and its location in the 3' untranslated region of the gene that contains it. The pathophysiological mechanism for multisystem degeneration in DM is not understood. In contrast to the profound muscle wasting that characterizes advanced DM, only minor histopathological abnormalities have occurred in DMPK knockout mice or in mice that overexpress a human DMPK transgene, making it unlikely that changes in DMPK activity provide a unitary explanation for the disease. A DNAse hypersensitive site that maps 0.7 kb downstream (centromeric) from the CTG repeats is eliminated on DM chromosomes. This finding indicates that the repeat expansion may alter the adjacent chromatin structure and raises the possibility that it may also affect the expression of flanking genes. An interesting candidate flanking gene is DMAHP, a recently discovered homeodomain-encoding gene. We show here that DMAHP expression in myoblasts, muscle and myocardium is reduced by the DM mutation is cis, and the magnitude of this effect depends on the extent of CTG repeat expansion. These observations support the hypothesis that DMAHP participates in the pathophysiology of DM.

Animals↗
PubMed1996

Zinc supplementation is associated with improved neurologic recovery rate and visceral protein levels of patients with severe closed head injury.

Sixty-eight patients were entered into a randomized, prospective, double-blinded controlled trial of supplemental zinc versus standard zinc therapy to study the effects of zinc supplementation on neurologic recovery and nutritional/metabolic status after severe closed head injury. One month after injury, the mortality rates in the standard zinc group and the zinc-supplemented group were 26 and 12%, respectively. Glasgow Coma Scale (GCS) scores of the zinc-supplemented group exceeded the adjusted mean GCS score of the standard group at day 28 (p = 0.03). Mean motor GCS score levels of the zinc-supplemented group were significantly higher on days 15 and 21 than those of the control group (p = 0.005, p = 0.02). This trend continued on day 28 of the study (p = 0.09). The groups did not differ in serum zinc concentration, weight, energy expenditure, or total urinary nitrogen excretion after hospital admission. Mean 24-h urine zinc levels were significantly higher in the zinc-supplemented group at days 2 (p = 0.0001) and 10 (p = 0.01) after injury. Mean serum prealbumin concentrations were significantly higher in the zinc-supplemented group (p = 0.003) at 3 weeks after injury. A similar pattern was found for mean serum retinol binding protein level (p = 0.01). A significantly larger number of patients in the standard zinc group had craniotomies for evacuation of hematoma; thus a bias may have been present. The results of this study indicate that zinc supplementation during the immediate postinjury period is associated with improved rate of neurologic recovery and visceral protein concentrations for patients with severe closed head injury.

Adolescent↗
PubMed1996

Kupffer cell depletion by gadolinium chloride enhances liver regeneration after partial hepatectomy in rats.

Although previous work suggests that tumor necrosis factor-alpha (TNF) promotes liver regeneration after partial hepatectomy (PH), the source of TNF is unknown. If Kupffer cells release TNF after PH, then Kupffer cell depletion by gadolinium chloride (GdCl) should inhibit liver regeneration. To test this hypothesis, cytokine expression and regenerative events were compared in GdCl-treated and control rats. Functional assays and Northern blot analysis of a Kupffer cell-specific mRNA confirmed that GdCl depleted Kupffer cells. Despite this, semiquantitative reverse transcription-polymerase chain reaction analysis of total hepatic RNA showed six- to eightfold higher levels of TNF transcripts in GdCl-treated rats. In this group, PH caused 12-to 16-fold greater induction of interleukin-6, a TNF-inducible cytokine, and two- to threefold greater induction of several cytokine-regulated genes (c-jun, C/EBP-beta, and C/EBP-delta). GdCl also amplified regeneration-associated increases in the DNA binding activity of AP-1, a growth regulatory transcription factor. Furthermore, hepatic incorporation of [3H]thymidine, expression of the S-phase antigen, proliferating cell nuclear antigen, and the hepatocyte mitotic index were each significantly greater in GdCl-treated rats. Thus, although GdCl causes Kupffer cell depletion, it does not decrease liver TNF and actually enhances liver regeneration after PH.

Animals↗
PubMed1994

Hyperphosphorylation of p53 induced by okadaic acid attenuates its transcriptional activation function.

The tumor suppressor and transcriptional factor p53 is a phosphorylated protein. Its phosphorylation states are regulated by several protein kinases and phosphatases. In this study, the wild-type p53 was transfected and expressed in chronic myelogenous leukemia K-562 cells. Incubation of the transfected cells with okadaic acid, an inhibitor of serine phosphatases 2A and 1, induced hyperphosphorylation of p53 protein. The treatment also increased the steady state level of p53 protein in the cells. However, the hyperphosphorylated p53 protein was less active in promoting transcription mediated by two p53-binding DNA elements, the ribosomal gene cluster and the p53 consensus DNA-binding sequence. Nevertheless, the decreased transcription activation was not due to decreased binding of p53 to these elements, as analyzed by mobility shift DNA-binding assays. In addition, the treatment did not induce a conformational change in p53, as assayed by two conformation-specific anti-p53 monoclonal antibodies, PAb240 and PAb1620. These results suggest that the phosphorylation induced by okadaic acid may selectively modulate the transcription activation function of p53. Consequently, phosphorylation may represent a mechanism of p53 inactivation in tumor cells that harbor the wild-type p53.

Base Sequence↗
PubMed1994

Nutritional and metabolic variables correlate with amino acid forearm flux in patients with severe head injury.

OBJECTIVE: To measure the arterial-venous amino acid flux across the forearm muscle in patients with severe head injury. DESIGN: Prospective, interventional study. SETTING: Level I trauma hospital in the neurosurgery intensive care unit (ICU) at a university medical center. PATIENTS: Eight nonsteroid-treated patients with severe head injury. INTERVENTIONS: Patients were prospectively randomized to receive either standard or supplemental intravenous zinc therapy. MEASUREMENTS AND MAIN RESULTS: Net forearm alanine, glutamine, tyrosine, phenylalanine, and branch-chain amino acid forearm flux were measured and compared with metabolic markers of energy expenditure and nitrogen excretion. There was a significant inverse relationship between the measured energy expenditure/predicted energy expenditure ratio and glutamine flux (r2 = .62; p < .05). The patients with the highest measured energy expenditure/predicted energy expenditure ratio had the greatest release of glutamine from forearm muscle. Nitrogen balance was significantly correlated with leucine flux (r2 = .53; p < .05) and with isoleucine flux (r2 = .67; p < .05). The patients with the most positive nitrogen balance had the least release of branch-chain amino acids from skeletal muscle. Tyrosine flux was highly correlated with net amino acid flux (r2 = .76; p < .01). Tyrosine flux was therefore indicative of overall muscle catabolism. Four patients had an overall negative flux of amino acids from skeletal muscle. Three patients had an overall negative flux of branch-chain amino acids. CONCLUSIONS: This preliminary descriptive report suggests that increased skeletal muscle efflux of amino acids correlates significantly with metabolic variables of hypermetabolism and hypercatabolism in nonsteroid-treated, head-injured patients.

Adult↗
PubMed1993

Cytokines and alcoholic liver disease.

It is clear that cytokines cause metabolic disturbances that are similar to known complications of AH. TNF appears to be a proximal mediator of multiple types of experimental liver injury and TNF activity is elevated in ALD, as are the levels of certain other cytokines. On the other hand, low physiologic amounts of cytokines appear to be important for liver regeneration (and perhaps are beneficial to the organism as a whole). Goals for evaluation of anticytokine therapy in ALD will be: (1) determining the timing and type of the particular anticytokine employed (such as, immediate administration of antibody followed by an inhibitor of cytokine production), (2) appropriate monitoring of drug effects on cytokine metabolism as well as liver function and outcome, and (3) maintenance of the regenerative or positive physiologic effects of cytokines while blocking the cytolytic effects. Thus, we predict that ultimate anticytokine therapy will be directed at conserving the positive growth-enhancing effects of cytokines while attenuating their cytolytic effects.

Animals↗
PubMed1993

Long-term ethanol consumption alters the hepatic response to the regenerative effects of tumor necrosis factor-alpha.

The pathogenesis of chronic alcoholic liver disease is uncertain, but it may reflect an impaired wound healing response to ethanol-induced liver injury. Cell-to-cell communication such as that mediated by the cytokine tumor necrosis factor is necessary for successful liver regeneration and complete recovery from liver injury. Hence disruption of intercellular regenerative signaling may contribute to the pathogenesis of chronic alcoholic liver disease. To test this hypothesis, the cytokine and regenerative responses triggered by partial hepatectomy were compared in ethanol-fed rats and isocalorically maintained, pair-fed controls. To further clarify the effect of ethanol on tumor necrosis factor-modulated regenerative effects, we evaluated some of the rats in each feeding group after pretreatment with antibodies to tumor necrosis factor. As expected, ethanol inhibited DNA synthesis and liver cell proliferation after partial hepatectomy. Ethanol-associated inhibition of liver regeneration occurred despite apparently similar serum concentrations of the tumor necrosis factor-inducible cytokine interleukin-6. Treatment with antibodies to tumor necrosis factor 1 hr before partial hepatectomy inhibited post-partial hepatectomy induction of interleukin-6 and liver regeneration in ethanol-fed and pair-fed rats. However, serum interleukin-6 was reduced more in ethanol-fed rats than in control rats (93% vs. 66%; p < 0.05). Antibodies to tumor necrosis factor also inhibited hepatic DNA synthesis more in ethanol-fed rats than in controls (85% vs. 50%; p < 0.05). In ethanol-fed rats, the increased effect of tumor necrosis factor antibody on post-partial hepatectomy DNA synthesis suggests heightened sensitivity of hepatocytes to tumor necrosis factor.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

The protective effect of FK506 pretreatment against renal ischemia/reperfusion injury in rats.

The effect of pretreatment with FK506 on renal ischemia and reperfusion (I/R) injury was investigated using a rat model. Animals were assigned to one of two groups (20 rats each). Group 1 animals (controls) received 0.5 ml saline while group 2 animals received FK506 (0.3 mg/kg), administered intravenously 24 hr prior to the induction of renal ischemia. A 60-min period of ischemia of the right kidney was induced, and upon reperfusion a left nephrectomy was performed. Blood samples for estimation of BUN, creatinine, and tumor necrosis factor were collected on days 0 (preischemia), 1, 2, 3, 5, 7, and 10 (postischemia). Rats were sacrificed after day 10 and renal tissue was examined histologically. All animals survived the ischemic episode. FK506 pretreatment significantly reduced the serum levels of BUN (P less than 0.02), creatinine (P less than 0.02), and TNF (P less than 0.05) as compared with that seen in controls. Histologically, at day 10, the kidneys showed the expected sequelae of prior renal I/R with various degrees of tubular damage. However, no objective differences were evident between the two groups. Based upon these data, it can be concluded that (1) FK506 pretreatment ameliorates the functional renal injury associated with I/R, (2) renal ischemia induces the release of TNF, and (3) FK506 pretreatment results in a significant inhibition of TNF production. These data suggest that the release of TNF may be responsible for the increasing of BUN and creatinine levels seen after renal I/R and that pretreatment of renal donors with FK506 may improve renal function in the immediate post-transplant period.

Animals↗
PubMed1992

Antibodies to tumor necrosis factor-alpha inhibit liver regeneration after partial hepatectomy.

Certain cytokines that are produced in liver may act as growth factors to facilitate wound healing and, hence, may influence liver regeneration. However, this hypothesis has not been directly tested. To determine whether the cytokine response evoked by partial hepatectomy (PH) modulates the process of liver regeneration, adult male rats were injected intraperitoneally with either goat polyclonal antibodies to rat tumor necrosis factor (TNF; 15 micrograms/g body wt) or an equal amount of goat anti-rat immunoglobulin G 1 h before PH. Animals were killed at 12, 24, 48, or 72 h post-PH, 1 h after injection with [3H]thymidine. Serum TNF levels were measured with the L929 cytotoxicity assay, titers of antibody to TNF were determined by enzyme-linked immunoabsorbent assay, and interleukin-6 (IL-6) concentrations were measured by B9 cell bioassay. Liver regeneration was assessed by [3H]thymidine incorporation into hepatic DNA and by immunohistochemical evidence of proliferating cell nuclear antigen (PCNA) expression. Antibodies to TNF were detected in treated rats but not in controls. Titers were highest at 12 h and progressively fell. Although TNF was never detected in serum, treatment with anti-TNF pre-PH significantly inhibited increases in serum IL-6 concentration post-PH. Anti-TNF pretreatment also inhibited [3H]thymidine incorporation into DNA, as well as expression of PCNA by both hepatocytes and liver nonparenchymal cells. These data indicate that TNF positively modulates liver regeneration after PH.

Animals↗
PubMed1992

FK 506 reduces the injury experienced following renal ischemia and reperfusion.

The effect of FK 506 pretreatment on renal ischemia and reperfusion (I/R) injury was investigated. Adult male rats were assigned to one of two groups (20 animals each). Group 1 (controls) received 0.5 mL saline while group 2 received FK 506 (0.3 mg/kg) intravenously 24 h prior to the induction of renal ischemia. After a 60-min period of ischemia of the right kidney, a left nephrectomy was performed. Blood for BUN, creatinine, and tumor necrosis factor (TNF) was obtained prior to ischemia and on days 1, 2, 3, 5, 7, and 10. All surviving animals were sacrificed at day 10. FK 506 pretreatment reduced the serum levels of BUN (p less than .02), creatinine (p less than .02) and TNF (p less than .05) as compared to that seen in controls. Based upon these data, it appears that: (a) renal ischemia induces the release of TNF; (b) FK 506 pretreatment inhibits TNF production; and (c) FK 506 reduces renal injury association with I/R.

Animals↗
PubMed1992

Nutrition and brain injury.

The patient with head injury must overcome central and systemic insults. In addition to the head injury itself, the patient suffers a systemic metabolic response to injury. Both of these insults can affect the patient's ability to survive and recover. During the past decade, investigators have described the systemic metabolic result identified by hypermetabolism, hypercatabolism, the acute-phase response, decreased immunocompetence, hyperglycemia, increased counterregulatory hormone levels, increased ventricular fluid and serum cytokine levels, and altered gastric function. During the next decade, investigators will attempt to modulate this response by manipulating the types of nutrients administered, use of pharmacologic and physiological agents, and administration of growth factors.

Brain Injuries↗
PubMed1991

Altered gastric emptying in the head-injured patient: relationship to feeding intolerance.

Most patients with moderate to severe head injury initially do not tolerate enteral feedings postinjury. This intolerance is more prolonged than that found in patients suffering other types of trauma. The authors prospectively evaluated 12 patients with moderate to severe head injury (Glasgow Coma Scale score between 4 and 10) throughout their hospitalization for liquid gastric emptying as a possible mechanism for intolerance to enteral feeding. During Week 1, the majority of patients displayed a delay in gastric emptying. Patients also displayed an abnormal biphasic response (gastric emptying faster than normal during the early stage but prolonged later). By Week 2, many patients still had delayed and abnormal biphasic responses to gastric emptying. By Week 3, an improvement was observed with the majority of patients exhibiting rapid gastric emptying, but delays and abnormal biphasic responses were still seen. Patients who initially had rapid or normal gastric emptying tolerated full-strength full-rate feedings significantly earlier compared with those who experienced delayed gastric emptying (8.5 +/- 0.5 days vs. 13.7 +/- 3.2 days, p less than 0.001). All patients tolerated full-strength full-rate feedings by Day 16 postinjury (range 7 to 16 days) except the two patients who displayed delayed gastric emptying for prolonged periods of time (mean 25 days). This is the first study to longitudinally evaluate gastric emptying following head injury. The authors suggest that patients with moderate to severe head injury often experience alterations in gastric emptying which may affect their ability to tolerate enteral feedings.

Adolescent↗
PubMed1991

Metabolic management of the patient with head injury.

Patients with severe head injury have a disruption in metabolic homeostasis that includes increased energy expenditure and increased protein catabolism. These changes have been suggested to occur secondary to steroid administration, immobility, and other factors. A review of investigations indicates that the head injury itself causes these metabolic changes, although steroid administration can further alter plasma amino acid changes. Altered plasma amino acid profiles after head injury may have an effect on substrate availability to the brain, bacterial translocation, and overall nitrogen balance. Patients with severe head injury have increased skeletal muscle efflux of amino acids. Lack of nutrient supplementation in these patients is associated with increased morbidity and mortality. Enteral nutrition is the preferred mode of feeding but often is not tolerated in the patient with head injury. Parenteral nutritional support can be given to these patients without worsening cerebral edema.

Amino Acids↗
PubMed1991

Increased plasma and ventricular fluid interleukin-6 levels in patients with head injury.

The cytokine interleukin-6 (IL-6) plays a major role in initiating the acute phase response, especially in the production of acute phase reactants such as C-reactive protein. The objectives of this study were to determine whether plasma or ventricular fluid IL-6 levels were elevated at time of admission after head injury and whether plasma IL-6 levels related temporally to clinical improvement of levels of acute phase reactants. Thirty patients with Glasgow Coma Scale (GCS) scores of 3 through 10 were observed for 15 days after head injury. Peak elevation of plasma IL-6 occurred on admission (85 +/- 12 U/ml; normal level is less than 2 U/ml) and then decreased during the hospital course to a level of 29 +/- 4 U/ml on day 15. Plasma IL-6 levels decreased significantly faster in patients with admission peak 24-hour GCS scores of 8 through 10 compared with patients with GCS score less than 8 (p less than 0.01). Patients had markedly elevated and variable ventricular fluid IL-6 levels on admission (mean 3880 +/- 2022 U/ml; normal, less than 2 U/ml). A temporal relationship was found between plasma IL-6 levels and multiple acute phase reactants thought to be mediated by IL-6. We conclude that plasma and ventricular fluid levels of IL-6 are elevated after head injury and that plasma IL-6 level is temporally related to acute phase reactants and clinical improvement. We suggest that IL-6 may play an etiologic role in many of the metabolic or nutritional sequelae of head injury.

Adolescent↗
PubMed1990

Gastrointestinal behavior of orally administered radiolabeled erythromycin pellets in man as determined by gamma scintigraphy.

The behavior of single 250-mg doses of a multiparticulate form of erythromycin base (ERYC(R)), each including five pellets radiolabeled with neutron-activated samarium-153, was observed by gamma scintigraphy in seven male subjects under fasting and nonfasting conditions. The residence time and locus of radiolabeled pellets within regions of the gastrointestinal tract were determined and were correlated with plasma concentrations of erythromycin at coincident time points. Administration of food 30 minutes postdosing reduced fasting plasma erythromycin Cmax and area under the plasma erythromycin versus time curve (AUC) values by 43% and 54%, respectively. Mean peak plasma concentration of erythromycin (Cmax) in the fasting state was 1.64 micrograms/mL versus 0.94 micrograms/mL in the nonfasting state. Total oral bioavailability, as determined by mean AUC (0-infinity) of the plasma erythromycin concentration versus time curve, was 7.6 hr/micrograms/mL in the fasted state, versus 3.5 hr/micrograms/mL in the nonfasting state. Mean time to peak plasma erythromycin concentration (tmax) in the fasting state was 3.3 hours, versus 2.3 hours in the nonfasting state. Plasma concentrations of erythromycin in both fasting and nonfasting states were within acceptable therapeutic ranges. Evidence provided by this study: 1) indicates that pellet erosion and absorption of active erythromycin base begins when the enteric-coated pellets reach the highly vascular mucosa of the jejunum and proximal ileum, and is essentially completed within the ileum, with a significant portion absorbed in the medial-to-distal ileum; 2) confirms that acceptable therapeutic plasma levels of erythromycin are attained in nonfasting subjects (Cmax = 0.94 microgram/mL) and that superior plasma erythromycin concentrations (Cmax = 1.64 micrograms/mL) are achieved by administration of the dose on an empty stomach 1 to 2 hours before or after meals; 3) corroborates other comparative studies reporting greater fasting bioavailability with this multiparticulate dosage form of erythromycin base than with reference single tablet or particle-in-tablet formulations; and 4) indicates that neutron activation of stable isotopes incorporated as a normal excipient in industrially-produced formulations provides an effective means for in vivo evaluation of dosage forms through gamma scintigraphy.

Administration, Oral↗