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Biomedical subjects

R Griffith

Publications and source records attributed to R Griffith.

At least 19 recordsLinked to original sources
PubMed1992

Simultaneous amplification and detection of specific DNA sequences.

We have enhanced the polymerase chain reaction (PCR) such that specific DNA sequences can be detected without opening the reaction tube. This enhancement requires the addition of ethidium bromide (EtBr) to a PCR. Since the fluorescence of EtBr increases in the presence of double-stranded (ds) DNA an increase in fluorescence in such a PCR indicates a positive amplification, which can be easily monitored externally. In fact, amplification can be continuously monitored in order to follow its progress. The ability to simultaneously amplify specific DNA sequences and detect the product of the amplification both simplifies and improves PCR and may facilitate its automation and more widespread use in the clinic or in other situations requiring high sample throughput.

Alleles↗
PubMed1990

Hemodynamic effects of 1-[3,4-dihydroxyphenyl]-1,2-diaminoethane versus norepinephrine during ventricular fibrillation and cardiopulmonary resuscitation.

We hypothesized that substitution of the hydroxyl group (OH) on the beta carbon of norepinephrine (NE) with an amino group would yield a compound, 1-(3,4-dihydroxyphenyl)-1,2-diaminoethane (DHPDAE), that would maintain the hemodynamic properties of NE during CPR, but would decrease the rate of post-defibrillation dysrhythmias. Six mixed breed swine weighing greater than 28 kg were studied. The animals were instrumented for cerebral (CBF) and myocardial blood flow (MBF) measurements. Ventricular fibrillation (VF) was induced. After 10 min of VF, CPR was begun. After 3 min of CPR, 2.5 mg/kg of DHPDAE was administered and CPR continued. Defibrillation was attempted 3.5 min after drug administration. CBF, MBF and defibrillation rates were compared to an historical control group receiving 0.16 mg/kg of NE. Outcome variables were compared using a Wilcoxon Rank Sum test and Fisher-exact test. NE significantly improved CBF and MBF compared to DHPDAE. All the animals in the NE group were successfully defibrillated into a perfusing rhythm. Sixty percent of the NE treated animals experienced post-defibrillation ventricular dysrhythmias. None of the animals in the DHPDAE were successfully defibrillated into a perfusing rhythm. Substitution of the hydroxyl group on the beta-carbon of NE with an amino group significantly decreases the hemodynamic properties of the parent molecule.

Animals↗
PubMed1989

Cell surface changes during electromagnetic field exposure.

Fibroblasts from 5 1/2-day-old chick embryos go through a sequential series of changes when exposed to a constant electromagnetic field (EMF) of 10 V/cm. These changes include rounding up, becoming bipolar in shape, assuming a cylindrical profile, elongating perpendicular to the EMF, and migrating to the cathode. These morphological changes are associated with changes of the cell surface, which include the formation of filopodia and extensive sheet-like contacts on the cathodic cell surface, the retraction of processes and the formation of focal contacts on the anodic cell surface.

Animals↗
PubMed1988

Effects of adherence, activation and distinct serum proteins on the in vitro human monocyte maturation process.

Elutriator-purified human monocytes were cultured in a serum-free (SF) medium, and various serum proteins and functional activating agents were assessed for their effects on the in vitro maturation of human monocytes to macrophages. Following 3 days of suspension culture in Teflon labware, 60% of the monocytes were easily recovered. When varying concentrations of human AB serum (HuAB) were employed, human monocyte maturation progressed rapidly; the kinetics of this maturation process during cell suspension culture were very similar to the pattern observed following adherence culture. In contrast, when SF medium was employed, a marked retardation of the monocyte maturation process was observed; this could not be attributed to any changes in cell recovery and/or viability. Thus, cells could be maintained in their monocytoid form for 3 days when cultured in SF medium. When HuAB was added after 3 days of culture, human monocyte maturation into macrophages proceeded at a normal rate. We attempted to characterize certain of the serum protein(s) found in HuAB which promoted the monocyte maturation process. Human immunoglobulin G (IgG) was found to be the most potent serum protein in increasing 5'-N activity and decreasing peroxidase activity of suspension cultured monocytes. Immunoglobulin M (IgM) and albumin (Alb) were shown not to have significant monocyte maturation activity. Heat-treated human gamma globulin and IgG purified by high-performance liquid chromatography (HPLC) were shown to have patterns identical with that of untreated HGG and IgG with regard to promoting monocyte maturation; F(ab')2 was not an active maturation promoter, indicating the need for an intact Fc portion of the IgG molecule. Fibrinogen and fibronectin also had maturation promoting activity. Finally, addition of the potent monocyte functional activators, muramyl dipeptide (MDP), polyriboinosinic:polyribocytidilic acid (Poly I:C), and lipopolysaccharide (LPS) had no effect on the monocyte maturation process. Thus, neither cell adherence or activation appear to be critical for the monocyte to macrophage maturation process. Instead, we hypothesize that in addition to proper nutritional support, a group of serum proteins (unified mainly by their ability to interact with monocyte membrane receptors) appear to be the principal promoters of this process.

5'-Nucleotidase↗
PubMed1987

Cervical spine stabilization in pediatric patients: evaluation of current techniques.

We evaluated the performance of commercially available infant and pediatric cervical collars, both alone and in combination with commonly used supplemental devices (eg, Kendrick Extrication Device, half-spine board). One infant and 11 pediatric-sized collars were tested on mannequins representing an infant and a 5-year old child. Maximum forces generated by cooperative children were measured, then applied to the mannequins to reproduce head and neck flexion, extension, rotation, and lateral motion. Limitation of motion was measured in each direction for each collar and combination method. In general, collars of rigid plastic construction performed better than did foam types. However, when used alone none of the collars provided acceptable immobilization, with even the best allowing 17 degrees flexion, 19 degrees extension, 4 degrees rotation, and 6 degrees lateral motion. When combined with supplemental devices, immobilization to 3 degrees or less in any direction could be achieved. Findings were verified using cooperative children and selected collars. Overall, combination methods were more effective than cervical collars alone (P less than .001) or supplemental devices alone (P less than .05). The modified half-spine board used with a rigid collar and tape was the most effective combination method. We conclude that prehospital cervical spine stabilization in pediatric patients is best accomplished using a rigid-type cervical collar in combination with supplemental devices as described.

Child↗
PubMed1986

High-dose chemotherapy, fractionated total-body irradiation, and allogeneic marrow transplantation for malignant lymphoma.

Seventeen patients with malignant lymphoma, including 13 with progressive disease and four in remission following primary chemotherapy, received high-dose chemotherapy, fractionated total-body irradiation (TBI), and allogeneic marrow transplants. Eleven of the 13 (85%) patients in relapse who received transplants achieved remission, and three remain disease free 41, 21, and 17 months later; one patient in second remission who received a transplant is disease free at 11 months. Thirteen patients are dead: four because of progressive lymphoma, seven because of interstitial pneumonitis, and two because of complications of severe acute graft-v-host disease. These results are similar to those noted in marrow transplantation series for advanced acute leukemia; since transplantation during remission has decreased relapse and improved survival in leukemia, earlier transplantation may produce improved results in lymphoma patients as well. However, the effectiveness of conventional therapy regimens for most lymphomas and the high incidence of severe transplant-related complications usually limit allogeneic transplantation to lymphoma patients in situations other than consolidation of first remission. Initial partial remission, early relapse from an initial remission, and perhaps second remission are situations in which conventional therapy is often ineffective, but the adverse features of very advanced lymphoma are not present; marrow transplantation may be considered in eligible patients. Transplant recipients with more advanced disease are anticipated to have poorer survivals.

Adolescent↗
PubMed1980

The role of radiation therapy in the management of plasma cell tumors.

A retrospective review is reported of 128 patients presenting with multiple myeloma and 16 patients presenting with solitary plasmacytoma. Ninety-one percent of 116 evaluable patients treated for palliation of painful bone disease received some degree of subjective pain relief. The radiation dose most frequently prescribed was between 1500 and 2000 rad. Of the 278 ports treated, only 17 (6.1%) were re-treated to the same area at a later date. There was no increase in incidence of re-treatment with lower radiation doses. Ten of the 13 patients treated for a solitary plasmacytoma with a minumum follow-up period of three years have local tumor control. The median survival in the solitary plasmacytomas is five and one-half years. Data from the literature on 27 additional solitary plasmacytomas combined with our data suggest an improved local control and a decrease in dissemination with doses greater than 5000 rad. It is concluded that low doses of radiation are usually adequate to treat painful bone lesions of multiple myeloma and doses of 5000-6500 rad in six to seven weeks are recommended for solitary plasmacytomas.

Adult↗
PubMed1979

Effect of alcohol and marijuana on eye movements.

The effects of alcohol and marijuana (tetrahydrocannabinol-THC) on saccades, smooth pursuit, and optokinetic nystagmus were quantitatively evaluated in 24 normal subjects using electro-oculographic recordings. Each subject was given an initial trial run and then tested three times (at weekly intervals) with either 0.0microgram THC or 100 microgram THC/kg bodyweight while at three different blood alcohol concentrations (0.0, 0.05 and 0.1%). A 2X3 factorial design was used. Saccades and smooth pursuit were induced by a dot of light moving in steps and ramps on a modified television set. Optokinetic nystagmus was induced by a cloth drum completely surrounding the subject and moving at a constant velocity of 30 degrees/s. Alcohol (0.05 and 0.1%) alone produced significant (p less than 0.05) impairment of saccade maximum velocity and reaction time, smooth pursuit velocity, and optokinetic slow-component velocity. The addition of THC caused performance to further deteriorate at each blood alcohol level but, in all but one instance, the added effect was not statistically significant ( greater than 0.05). At the THC and alcohol concentrations used in this study, the eye movement effects of alcohol over-shadowed those of marijuana.

Adult↗
PubMed1976

Fluid-percussion model of mechanical brain injury in the cat.

Mechanical brain injury was produced in 36 cats with a fluid-percussion model in which brain damage or dysfunction is produced by a single, brief, hydraulically-induced pressure transient that is conducted through the brain. Fluid-percussion injury induce elastic deformation of the brain resembling the brain deformation known to occur following head impact. Physiological responses and pahtological changes following injury were expressed as a function of peak pressure. Macroscopic central nervous system lesions concentrated at the pontomesencephalic junction, cervicomedullary junction, and in the cerebellar tonsils were consistently observed at and above 2.6 atmospheres (atm). At higher levels of injury (greater than or equal to 3.2 atm) there was extensive basal subarachnoid hemorrhage. At very high levels of injury (greater than 4.0 atm) hemorrhagic contusions were noted at the cerebral hemisphere impact site. A spectrum of neuronal alterations was identified in the damaged areas. Computer analysis showed correlation of electroencephalographic (EEG) changes with the neuropathological changes, since EEG recovery became severely impaired above 2.6 atm. No EEG changes were noted below 1.5 atm. From 1.5 to 2.2 atm there was a physiological response to injury but no significant changes were seen on neuropathological examination. This range of injury should permit further studies of the more subtle changes following mechanical brain injury without intraparenchymal hemorrhage or subarachnoid hemorrhage. The fluid-percussion model relates brain deformation following mechanical loading to a single pressure transient that is easily measured and controlled. Further quantitative investigation into the pathobiology of mechanical brain injury following graded brain deformation is thus made possible.

Animals↗