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Biomedical subjects

C G Jackson

Publications and source records attributed to C G Jackson.

At least 55 records · Page 3Linked to original sources
PubMed1995

CD4+/CD8+ T-lymphocyte ratio: effects of rehydration before exercise in dehydrated men.

Effects of fluid ingestion on CD4+/CD8+ T-lymphocyte cell ratios were measured in four dehydrated men (ages 30-46 yr) before and after 70 min of supine submaximal (71% VO2max) lower extremity cycle exercise. Just before exercise, Evans blue dye was injected for measurement of plasma volume. The subjects then drank one of six fluid formulations (12 ml.kg-1) in 3-4 min. All six mean posthydration (pre-exercise) CD4+/CD8+ ratios (Becton-Dickinson Fluorescence Activated Cell Sorter and FACScan Consort-30 software program [San Jose, CA]) were below the normal range of 1.2-1.5; mean (+/- SE) and range were 0.77 +/- 0.12 and 0.39-1.15, respectively. The post-exercise ratios increased: mean = 1.36 +/- 0.15 (P < 0.05) and range = 0.98-1.98. Regression of mean CD4+/CD8+ ratios on mean plasma osmolality resulted in pre- and post-exercise correlation coefficients of -0.76 (P < 0.10) and -0.92 (P < 0.01), respectively. The decreased pre-exercise ratios (after drinking) were probably not caused by the Evans blue dye but appeared to be associated more with the stress (osmotic) of dehydration. The increased post-exercise ratios to normal levels accompanied the rehydration and were not due to the varied electrolyte and osmotic concentrations of the ingested fluids or to the varied vascular volume shifts during exercise. Thus, the level of subject hydration and plasma osmolality may be factors involved in the mechanism of immune system modulation induced by exercise.

Adult↗
PubMed1994

Facial nerve neuromas presenting as acoustic tumors.

Facial nerve tumors can present as masses in the internal auditory canal or cerebellopontine angle and may mimic an acoustic neuroma. These tumors can occur in any segment of the nerve from the brain stem to the neuromuscular junction. Prior to the advent of computed tomography and magnetic resonance imaging with gadolinium, facial nerve tumors were often difficult to diagnose. Even with these modalities it may be difficult to distinguish preoperatively between an acoustic neuroma and a facial schwannoma. Particular signs and symptoms associated with facial nerve tumors (in the spasms, and a facial tic. These symptoms, combined with modem radiologic studies, should allow for more accurate diagnosis, patient counseling, and treatment. This report presents a series of 32 facial nerve tumors diagnosed and treated at The Otology Group from 1975 to 1992. Of these lesions, 12 (38%) were thought to be acoustic neuromas. Eighteen tumors were correctly identified preoperatively as facial nerve tumors. Two facial nerve tumors were found incidentally.

Adult↗
PubMed1993

Thyroplasty in the functional rehabilitation of neurotologic skull base surgery patients.

Definitive management of lesions of the lateral cranial base is surgical. Functional outcome is dependent on cranial nerve preservation. In 1988 an effort was made to decrease the incidence of tracheotomy, the duration of hospital stay, and the period prior to unassisted oral intake, by establishing more immediate acquisition of glottic competence through laryngeal rehabilitation. The experience of one author (JLN) in over 40 phonosurgical procedures under local anesthesia is presented. Although tracheotomy provides excellent airway protection, it is accompanied by substantial morbidity. The technique of phonosurgery has dramatically improved recovery and functional outcomes of neurotologic skull base surgery patients, enabling them to realize "cure" rather than "control" of their disease.

Adult↗
PubMed1992

Design and synthesis of some substrate analogue inhibitors of phospholipase A2 and investigations by NMR and molecular modeling into the binding interactions in the enzyme-inhibitor complex.

A series of substrate analogue inhibitors of pancreatic phospholipase A2 has been designed and synthesized. The compounds were tested in a novel dual-screening system based on parallel assays with monomeric and micellar substrates. Intermolecular nuclear Overhauser effects between vinylic protons on one inhibitor and identified active site residues on the bovine pancreatic enzyme have been observed in solution NMR studies of the enzyme-inhibitor complex. It can be deduced from both the biochemical results and the NMR data that the mode of interaction between this type of inhibitor and the active site of phospholipase A2 is essentially the same, irrespective of the presence or absence of an aggregated phospholipid surface. A model of the binding between the enzyme and inhibitor which incorporates the two-dimensional NMR data has been developed. The model can account for the activity of modified inhibitor structures and can be extrapolated to an assessment of the mode of binding of the natural substrate itself.

Animals↗
PubMed1992

Bombesin stimulates the rapid activation of phospholipase A2-catalyzed phosphatidylcholine hydrolysis in Swiss 3T3 cells.

In Swiss 3T3 fibroblasts bombesin stimulated the release of arachidonic acid in a time- and dose-dependent manner. Arachidonate levels were significantly elevated after only a 2-s stimulation with the agonist. Furthermore, by measuring the arachidonate content of cellular phospholipids after cell activation, it was shown that there was selective depletion from phosphatidylcholine over the same time course. The corresponding production of lysophosphatidylcholine suggested the involvement of a phosphatidylcholine-specific phospholipase A2. Initial arachidonic acid release was not dependent on the presence of extracellular calcium, not activated by treatment of the cells with thapsigargin, and was unaffected by down-regulation of protein kinase C activity, or by treatment of the cells with the protein kinase C inhibitor staurosporine. These data strongly suggest that occupation of the bombesin receptor is closely coupled to activation of phospholipase A2 which results in the rapid release of arachidonic acid from phosphatidylcholine.

3T3 Cells↗
PubMed1992

Swallowing problems after excision of tumors of the skull base: diagnosis and management in 12 patients.

Acute-onset dysphagia can be a debilitating complication of operative intervention in skull base surgery. A retrospective study performed at Baptist Hospital investigated the oropharyngeal deficits, compensatory swallow techniques, and diet modifications of 12 patients who had undergone excision of skull base tumors. Oropharyngeal dysfunction, reduced laryngeal elevation, and copious pharyngeal retention were the most prominent swallowing deficits. Aspiration occurred in 75% of the patients studied. The most frequently employed compensatory swallow techniques were head turns to the affected side, supraglottic swallow, double swallows, alternating liquids and solids, carbonated beverage swallows, and small bolus size. Approximately 2 weeks following skull base surgery, 58% of the patients were able to tolerate oral intake with the aid of compensatory swallow techniques and diet modifications. Only 1 patient in this group remained unable to tolerate food by mouth. This paper focuses on identification of the disordered components of the swallow and the therapeutic management techniques characteristic of the patient who has undergone excision of a skull base tumor.

Adult↗
PubMed1992

Postoperative radiographic evaluation after acoustic neuroma and glomus jugulare tumor removal.

The role of postoperative radiographic follow-up of patients after acoustic neuroma or glomus jugulare tumor removal is unclear and not standardized. The incidence of both lesions is rare and recurrence thought to be unusual. However, a patient with an acoustic neuroma arising in the same ear afflicted with a glomus jugulare tumor removed 5 years earlier prompted a retrospective review of 999 acoustic neuroma and 98 glomus jugulare tumor patients. This review helps to determine the role and frequency of postoperative follow-up, not only to assess recurrence of these lesions but to monitor for the possible development of potential clinically silent new lesions.

Adult↗
PubMed1992

Defect reconstruction and cerebrospinal fluid management in neurotologic skull base tumors with intracranial extension.

Intracranial extension (ICE) is the spread of tumor into the subarachnoid space through dura or along cranial nerve roots. The single-stage removal of the skull base tumor with its ICE has been confounded by cerebrospinal fluid management and defect reconstruction. The purpose of this report is to review a current protocol for managing the cranial base tumor and its ICE as a unit. The ventricular shunting paper of 1987 is retracted. All tumors were managed at a single stage. Defect reconstruction was size dependent. Ninety-eight neurotologic skull base tumors with ICE were managed from 1971 to 1991. The new protocol was initiated in 1987. Results specific to this group are highlighted. For glomus tumors, cerebrospinal fluid leak rates have been dramatically reduced overall from 14.5% to 4%. The leak rates for nonglomus tumors, overall, have improved slightly. Complications are discussed. The development of this surgical approach protocol improves the functional outcome in patients of surgeons who aspire to disease "cure" rather than "control."

Adolescent↗
PubMed1991

An analysis of the retrolabyrinthine vs. the retrosigmoid vestibular nerve section.

Vestibular neurectomy is gaining widespread acceptance as a primary means of controlling medically refractory vertigo. However, debate continues over the adequacy of vestibular neurectomy within the cerebellopontine angle, long-term control, and the most appropriate surgical approach. To address these issues, we retrospectively reviewed 118 patients who underwent vestibular neurectomy between October 1984 and January 1988. Forty-two patients who underwent a retrolabyrinthine approach and 44 patients who underwent a retrosigmoid approach completed a written questionnaire and provided a recent audiogram. According to American Academy of Otolaryngology-Head and Neck Surgery guidelines, complete or substantial vertigo control was achieved and maintained in 95% of patients in both surgical groups. Hearing, tinnitus, and fullness results over the long term are variable. The advantages and disadvantages of the various vestibular neurectomy approaches will be detailed. On review of our results and surgical experience, we now prefer the retrosigmoid approach.

Adult↗
PubMed1991

Cranial nerve preservation in lesions of the jugular fossa.

The most significant objection to the proposal of lateral transtemporal cranial base surgery for the treatment of jugular foramen tumors is the perceived lasting morbidity attendant to aggregate cranial nerve loss. As techniques become more standardized and earlier diagnosis generates smaller tumors for treatment, outcome has become more predictable. Surgery has become the recognized management preference for these cranial base lesions. The purpose of this article is to assess the role of surgery in the treatment of jugular foramen lesions, as well as to review some of the technical highlights of conservation surgery, its clinical prerequisites, and reasonable expectations. We review 100 lateral skull base surgical cases of lesions involving the jugular foramen. The majority of these lesions--77 of 100--were paragangliomas. For these glomus tumors, cranial nerve preservation correlated well to tumor size and location. The diversity of the remaining 23 cases prevented any substantive conclusions.

Adolescent↗
PubMed1990

Skeletal muscle fiber area alterations in two opposing modes of resistance-exercise training in the same individual.

The purpose of this study was to observe fiber area changes that might occur in the same subject from two opposing resistance-exercise training regimes isolating the quadriceps muscle group. Twelve college-age men divided into two groups participated in each of two 7.5-week regimens; one performed a muscular strength program (high-resistance, low-repetition) 4 days a week on a resistance-exercise apparatus, while the other performed a muscular endurance (low-resistance, high-repetition) program. After a 5.5-week hiatus, the groups changed regimens for the second 7.5 weeks. Closed-needle biopsies of the dominant vastus lateralis and isokinetic dynamometer evaluations were made before and at the end of each training period. The muscle samples were analyzed for area changes. In both groups the initial exercise stimulus, whether for strength or endurance, increased the area of fibers of all three major types (I, IIA, and IIB). Subjects doing strength exercises as their second treatment showed a further increase in the area of type I and IIB fibers, whereas those doing endurance exercises showed a decrease in all fiber types. From the first to the last biopsy all fiber areas were decreased (P less than 0.05) in the control-strength-endurance group and increased (P less than 0.05) in the control-endurance-strength group. These results suggested that endurance exercise preceding strength exercise in an isolated muscle group maximized fiber area adaptations to exercise stress. Consideration should thus be given in exercise and rehabilitation programs to the muscle cellular adaptations evidenced in different orders of training, particularly if muscular strength is considered important.

Adenosine Triphosphatases↗