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Biomedical subjects

R L Saunders

Publications and source records attributed to R L Saunders.

At least 37 records · Page 2Linked to original sources
PubMed1990

Influence of ration level and salinity on circulating thyroid hormones in juvenile Atlantic salmon (Salmo salar).

Following acute exposure to seawater (30 ppt), plasma thyroxine (T4) of Atlantic salmon (Salmo salar) smolts increased 80% in the first 6 hr, declined to initial levels after 24 hr, and remained stable for 18 days thereafter. In nonsmolts, plasma T4 did not rise immediately after exposure to seawater, fell slightly after 2 days, and remained low for 18 days. Plasma triiodothyronine (T3) of smolts and nonsmolts was not affected by acute exposure to seawater. To examine the effect of long-term adaptation to ration and salinity, Atlantic salmon smolts were acclimated to three salinities (0, 10, and 30 ppt) and four ration levels (0, 0.2, 0.8, and 1.6% wet weight per day) for 6 weeks. Plasma T4 increased with increasing ration level (P less than 0.001) but was not significantly affected by salinity (P = 0.4). Plasma T3 also increased with increasing ration (P less than 0.001) and was more strongly correlated with ration level (r = 0.85) and growth rate (r = 0.88) than was plasma T4 (r = 0.73 and 0.75, respectively). At low ration (0 and 0.2% per day), fish in 10 ppt had slightly but significantly lower plasma T3 than fish in 0 ppt. There was no effect of salinity on plasma T3 at the higher rations, nor did plasma T3 levels differ significantly in fish in 0 and 30 ppt at any ration. The results indicate that ration level is a more important influence on circulating levels of plasma thyroid hormones than is salinity.

Animals↗
PubMed1988

Magnetic resonance imaging in the diagnosis and treatment of Lhermitte-Duclos disease (dysplastic gangliocytoma of the cerebellum).

Lhermitte-Duclos disease is a rare disorder characterized by a slowly enlarging mass lesion in the cerebellum. The pathophysiology of the disease is poorly understood, but recent reports have suggested that a clinically significant mass may recur many years after total gross removal of the tumor. Computed tomography and angiography have been relatively insensitive in imaging the tumor either at presentation or during the postoperative period. The authors present three patients with histologically proven Lhermitte-Duclos disease who have undergone magnetic resonance imaging (MRI). In the first case, preoperative T1- and T2-weighted images clearly demonstrated the location and extent of the lesion, which was verified at operation. In the other two cases, only postoperative images were obtained. These demonstrated the extent of residual tumor and indicate a high probability of lesion expansion during periods of 4 and 10 years, respectively. We conclude that MRI is an important tool in both the diagnosis and the treatment of patients with Lhermitte-Duclos disease.

Adult↗
PubMed1988

Use of implantable pumps for central nervous system drug infusions to treat neurological disease.

Increasing knowledge of the neurochemical aspects of central nervous system function raises the possibility of treating neurological disease by the appropriate manipulation of neurotransmitters, neuromodulators, and neurohormones. Clinical application of this knowledge has been inhibited, however, by long-standing problems with drug delivery to the central nervous system (CNS). The availability of implantable drug infusion pumps and stereotactic catheter placement techniques may overcome many of these problems. The problems of drug delivery to the brain and the present and potential uses of implantable drug pumps for neurological disease are discussed. In addition, the relationship between CNS drug infusion and neural tissue transplantation is briefly reviewed.

Brain Neoplasms↗
PubMed1987

External ventricular drainage for initial treatment of neonatal posthemorrhagic hydrocephalus: surgical and neurodevelopmental outcome.

Thirty-seven infants were treated for posthemorrhagic hydrocephalus (PHH) with external ventricular drainage (EVD) in 1977-1985. The mean age at EVD placement was 13 days; the mean duration of drainage was 21 days, and an average of 1.8 drains was used per patient. Complications were apnea (10%), hemorrhage (8%) and ventriculitis (6%). Ten infants died from pulmonary disease unrelated to the surgery. Thirty-two percent of the survivors did not require a permanent shunt. Neurodevelopmental outcome was evaluated at a mean age of 38 months. Eighteen of the twenty-seven survivors (67%) had normal cognitive function, 3 had borderline and 6 (22%) had moderate to profound mental retardation. Nine of the children (33%) had a normal neuromuscular exam. One child had mild, 11 had moderate and 6 had severe cerebral palsy. Four children had serious visual impairment. The worst outcomes were in the children with parenchymal or large intraventricular hemorrhages.

Cerebral Hemorrhage↗
PubMed1986

The effect of temperature on the vitellogenic response in Atlantic salmon post-smolts (Salmo salar).

Effects of low (3 degrees) and high (10 degrees) temperatures on the vitellogenic response to estradiol treatment were analyzed in female and male salmon post-smolts. Vitellogenic response as indicated by levels of circulating vitellogenin, hepatic protein, RNA, and nuclear count depends on the ambient temperature during hormone treatment but not on the previous 1 month acclimation temperature. Thus, the level of vitellogenin in the serum or hepatic RNA did not increase above the levels of the untreated controls in previously warm-acclimated smolts if the fish were exposed to low temperature water during treatment with estradiol. Conversely, cold-acclimated smolts showed increased levels of hepatic RNA and circulating vitellogenin only when transferred to 10 degrees water during treatment. No such response could be elicited if salmon were kept at 3 degrees during estradiol treatment. The negative influence of low ambient temperature on the vitellogenic response could not be eliminated by using higher doses of estradiol. Salmon post-smolts, long-term acclimated to 3 degrees revealed a significant vitellogenic response to estradiol only if the temperature during treatment was increased to 10 degrees. Estradiol treatment at 10 degrees stimulated the growth of liver as determined by the increase in liver somatic index and amounts of total hepatic protein, RNA, and nuclear count. On a per unit liver wet weight basis, however, only RNA increased above the level of the untreated control fish. As the nuclear count per gram of liver is similar in estradiol-treated and untreated groups, estradiol-induced liver growth in the salmon post-smolts may be accounted for by an increase in cell number (hyperplasia) rather than an increase in cell size (hypertrophy).

Animals↗
PubMed1986

Table-fixed retractor system for noncranial surgery. Technical note.

A retractor system based on the principle of table fixation of the retraction device has been fabricated and utilized in a broad range of noncranial procedures. Based on the refinement of self-retaining brain retractor methods, this device allows an atraumatic fixed exposure without the danger of "self-retained devices" impaling soft tissue and the compromises of hand-held retractors.

Neurosurgery↗
PubMed1986

Continuous intrathecal hydromorphone and clonidine for intractable cancer pain.

The use of hydromorphone and clonidine, delivered intrathecally by an implanted infusion pump, is described in a patient with intractable cancer pain. The patient was a 48-year-old woman with uterine cervical cancer-related pain that was poorly responsive to conventional oral narcotics. Hydromorphone was used because of the patient's history of morphine intolerance. When progressive intrathecal hydromorphone dosages were required, intrathecal clonidine (an alpha 2 adrenergic agonist) was infused concomitantly. Intrathecal hydromorphone and clonidine successfully controlled this patient's pain without the necessity to resort to destructive neurosurgery.

Carcinoma↗
PubMed1985

A cranial nail for fetal shunting.

A small number of human fetal hydrocephalics have been treated by ventriculoamniotic shunts of silastic tubing. The Colorado device appears to be the one most commonly used. The original experimental device tested on a primate model resembled a hollow shingle nail. This was designed by Michedja and Hodgen, contained a spring valve, measured approximately 32 X 4 mm and was placed by hysterotomy. An attractive feature of this design was its fixation by impaction in the skull, preventing displacement by fetal activity, a reported disadvantage with the silastic devices. To our knowledge, no one has used this nail-like design and tailored it to transuterine percutaneous placement in a human case.

Adult↗
PubMed1985

Tympanic membrane sensation.

Sensation from the tympanic membrane is generally believed to be mediated via at least four cranial nerves, some authors describing discrete territories for each of these nerves. The lack of critical evidence for independent sensory areas prompted a clinical study of tympanic membrane sensation in 32 patients having known cranial nerve deficits. Tympanic membrane sensation was tested in four quadrants using a 300 mg bristle under a Zeiss operating microscope. The findings were highly suggestive of a predominantly nociceptive system. Any change relative to the opposite tympanum was usually anaesthesia. No complete trigeminal deficit retained perception in all tympanic quadrants. Facial, glossopharyngeal and vagal deficits alone never affected tympanic sensation. These findings support the trigeminal nerve as the principal sensory nerve to the tympanic membrane, supplemented only inconstantly and incompletely by the other cranial nerves.

Adolescent↗
PubMed1985

Spontaneous cerebrospinal fluid otorhinorrhea.

Spontaneous cerebrospinal fluid (CSF) otorrhea implies the observation of CSF draining from the ear or nose without any previous history of traumatic or infectious etiology. The term does not exclude embryologic or developmental abnormalities. The condition may be life-threatening. Thus far it has been reported about twenty times. Because it is rare, misdiagnosis or failure to make a timely early diagnosis is common and proper therapy may be delayed. The purpose of this article is to review pertinent literature on this subject and to present two additional case reports. Emphasis will be placed on accuracy of diagnosis and on the surgical technique employed in repair of the discovered defect.

Cerebrospinal Fluid Otorrhea↗
PubMed1984

Outcomes and complications of continuous intraspinal narcotic analgesia for cancer pain control.

Preliminary reports of continuous intraspinal morphine analgesia have been enthusiastic regarding the resultant cancer pain control. Reports of continuous intraspinal infusion have not documented the duration of useful analgesia, need for concomitant analgesic therapies, or complication rates. Thus, the overall outcomes and complications of six chronic intrathecal and eight epidural morphine infusions were analyzed in the first 14 cancer pain patients implanted with continuous intraspinal morphine infusion reservoirs at this clinic. A five-point scale was used to assess the analgesic therapy required to maintain pain control during three consecutive intervals of intraspinal morphine infusion (zero to two months, two to six months, after six months). Comparison with pre-implant narcotic requirements revealed equal or reduced narcotic use for up to six months of therapy, with a definite trend toward escalation of intraspinal narcotics, systemic analgesia, and adjunctive procedures after two months. This occurred most likely due to narcotic tolerance and disease progression. Failure of pain control was the rule with continuous intraspinal morphine after six months. Three patients ultimately required neurolytic blocks. No clear difference was found in pain control requirements between epidural and intrathecal morphine infusion. No infection or respiratory depression occurred as a direct result of the intraspinal morphine implanted system.

Aged↗
PubMed1984

Preliminary report: intracranial cholinergic drug infusion in patients with Alzheimer's disease.

After toxicity studies in dogs, a preliminary feasibility trial of the continuous intracranial infusion of a muscarinic agonist was begun in four patients with biopsy-documented Alzheimer's disease. During the last 8 months, a totally implantable infusion system has been used to deliver bethanechol chloride into the cerebrospinal fluid of these patients at doses of 0.05 to 0.7 mg/day. Complications have been few and resolved spontaneously or were easily reversible. The subjective response to this treatment has been encouraging, with reports of improved cognitive and social function during drug infusion and a return to base line function with single-blind saline placebo infusions. Obviously, further evaluation will be necessary to demonstrate the efficacy of this treatment, and a double-blind placebo-controlled crossover trial is now being done. However, we think the preliminary results are encouraging and warrant the consideration of this approach as a potential treatment in patients with Alzheimer's disease.

Aged↗
PubMed1984

Use of cryoprecipitate coagulum to control tumor-bed bleeding. Case report.

The case is presented of a 44-year-old woman who underwent reoperation under cardiac standstill for a recurrent left sphenoid wing meningeal hemangiopericytoma. Because of persistent accumulations of clot with clinical deterioration and shift on computerized tomography scanning, the patient was returned to the operating suite twice. At the second reoperation, hemostasis was finally achieved through the instillation of admixed cryoprecipitate, calcium, and activated thrombin.

Adult↗