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Biomedical subjects

M D Johnson

Publications and source records attributed to M D Johnson.

At least 199 records · Page 11Linked to original sources
PubMed1990

Corneal-scleral melt in association with cataract surgery and intraocular lenses: a report of four cases.

Four patients with rheumatoid arthritis had cataract extraction with implantation of an intraocular lens (IOL). Postoperatively three patients developed progressive scleromalacia perforans. All three cases required patch grafting of the sclera and two of them developed progressive melting of the sclera and graft. The fourth case involved progressive corneal melting with extrusion of the IOL despite treatment with penetrating keratoplasties. All four cases developed retinal detachments with loss of vision and three of the eyes were subsequently enucleated. We describe each case and discuss the clinicopathologic correlations of this condition. The need for careful evaluation of rheumatoid arthritis patients with cataract surgery and IOL implantation is emphasized.

Aged↗
PubMed1990

Anaesthetic management of myocardial infarction in a parturient.

Myocardial infarction is encountered rarely during pregnancy, but when it occurs the event is life-threatening to both mother and fetus. Data on maternal and fetal outcome are limited, but overall maternal mortality approaches 35%, and 40% of deaths occur during the third trimester. We present a case of myocardial infarction occurring at 38 weeks gestation, and discuss the anaesthetic management of the problems encountered during labour and delivery.

Adult↗
PubMed1990

The prospective use of population pharmacokinetics in a computer-driven infusion system for alfentanil.

Maitre et al. recently evaluated the accuracy of a set of previously determined population pharmacokinetic parameters for the opioid alfentanil using data from an earlier study in which the drug had been administered using a computer-controlled infusion pump (CCIP). The present study evaluated the accuracy of these same parameters in a CCIP prospectively in two groups of clinically dissimilar patients: 29 healthy female day surgery patients and 11 relatively older and less healthy male inpatients. In addition, another set of pharmacokinetic parameters, previously determined by Scott et al. in the CCIP in 11 male inpatients was also evaluated. The bias and inaccuracy were assessed by the median performance error (MDPE) and the median absolute performance error (MDAPE) in which the performance error was determined as the difference between measured and target serum concentration as a fraction of the target serum concentration. Unlike Maitre et al., the current study found a consistent bias in both populations. The MDPE was +53% and the MDAPE was 53%, with no difference between patient groups. In the 11 patients studied using the Scott et al. pharmacokinetic parameters, the MDPE was +1% and the MDAPE was 17%. The parameters of Scott et al. were further tested by simulating the serum concentrations that would have been achieved had they been used in the CCIP in the first 40 patients; results indicated MDPE of +2% and an MDAPE of 18%. Therefore, reasonably reliable and accurate target serum concentrations of alfentanil can be achieved using the pharmacokinetic parameters of Scott et al. in a CCIP.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Chloroprocaine antagonism of epidural opioid analgesia: a receptor-specific phenomenon?

Sixty healthy patients scheduled for elective cesarean delivery under epidural anesthesia were randomized to receive either lidocaine or 2-chloroprocaine as the primary local anesthetic agent. When patients first complained of postoperative pain in the recovery room, they were given either fentanyl 50 micrograms or butorphanol 2 mg, epidurally, in a randomized, blinded fashion. Postoperative analgesia, quantitated on a visual analogue scale, as well as time elapsed until first request for supplemental opioid, did not differ for patients receiving butorphanol after either 2-chloroprocaine or lidocaine anesthesia. In contrast, epidural fentanyl produced a shorter and lesser degree of sensory analgesia after 2-chloroprocaine use, whereas epidural fentanyl after lidocaine anesthesia provided pain relief similar to that seen in the butorphanol groups. Side effects were limited to somnolence with butorphanol and pruritus with fentanyl. No evidence of respiratory depression was seen in any patient. We conclude that 2 mg of butorphanol epidurally provides approximately 2 to 3 h of effective analgesia after cesarean delivery with either lidocaine or 2-chloroprocaine anesthesia. Epidural fentanyl seems to be antagonized when 2-chloroprocaine, but not lidocaine, is used as the primary local anesthetic agent. We suggest a possible mu-receptor-specific etiology for this effect.

Adult↗
PubMed1990

Fulminant monophasic multiple sclerosis, Marburg's type.

The clinical, neuroradiological and necropsy findings are described in a 49 year old woman with long-standing idiopathic pulmonary haemosiderosis and acute monophasic multiple sclerosis (Marburg's type). Progression of the demyelinating process produced blindness and paraplegia over three weeks. At five weeks, magnetic reasonance imaging (MRI) studies showed lesions in the pons and left occipital lobe. The patient died 10 weeks after onset of symptoms. Necropsy examination revealed acute plaques in the optic chiasm, and the white matter around the lateral and fourth ventricle and spinal cord. Similarities between this and previously described cases of Marburg's disease are discussed.

Axons↗
PubMed1990

Effects of naloxone on renin and pressor responses to acute renal hypotension in rats.

Reduction of renal perfusion is followed by increases in plasma renin activity (PRA) and arterial pressure. The present experiments were designed to determine if an opiate antagonist would alter pressor or renin responses to acute reduction of renal arterial pressure (RAP) in anesthetized rats. Male Sprague-Dawley rats were anesthetized with Inactin, and an adjustable constrictor device was placed around the abdominal aorta proximal to the renal arteries. One-half of the animals were pretreated with the opiate antagonist naloxone (2 mg/kg iv), and the other one-half were pretreated with saline vehicle. The abdominal aorta was then constricted to reduce RAP by 25% (measured as femoral arterial pressure) in one-half of the animals in each pretreatment group. Compared with vehicle pretreatment, naloxone pretreatment did not alter the PRA response to aortic constriction; however, naloxone did attenuate the pressor response. We conclude that 1) the PRA response to acute reduction of renal arterial pressure is not dependent on an opiate mechanism in the rat, and 2) attenuation of the pressor response to aortic constriction by naloxone in intact rats is not secondary to a suppression of the PRA response.

Analysis of Variance↗
PubMed1990

Role of epinephrine in the development of hypertension in Dahl salt-sensitive rats.

The present experiments were designed to test the hypothesis that adrenal epinephrine contributes to the development of hypertension in the Dahl salt-sensitive (DS) rat. All studies were carried out in conscious male DS and Dahl salt-resistant (DR) rats weighing 200-240 g. An indwelling femoral arterial catheter was placed for blood sampling and measurement of blood pressure. After 5 days of either a high salt (7% NaCI) or a normal salt (1% NaCl) dietary regimen, DS and DR rats were subjected to an acute stress paradigm (graded electrical footshock). There were no differences in basal plasma catecholamine concentrations or in the acute pressor responses to graded footshock between the four substrain/diet groups. However, in both DS and DR rats, plasma epinephrine responses to acute footshock were greater on a 7% than on a 1% NaCl diet. Additional groups of DS rats were treated with an inhibitor of adrenal phenylethanolamine N-methyltransferase, SK&F 29,661 (1-2 g/kg body wt/day) or with vehicle. Three days after placement of an arterial catheter, rats were placed on a 7% NaCl diet, and blood pressure was measured daily for an additional 3 weeks. Although SK&F 29,661 treatment was effective in reducing adrenal epinephrine content and apparent release by approximately 80%, treatment did not alter the time course of salt-induced changes in blood pressure.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Lipocortin-1 immunoreactivity in the human pituitary gland.

We evaluated the distribution of lipocortin-1 immunoreactivity in 118 immature or mature human hypophyses using the peroxidase-antiperoxidase (PAP) technique with a polyclonal rabbit antiserum against lipocortin-1. Serial sections were evaluated for five pituitary hormones and S-100 protein immunoreactivity to compare their distributions with that of lipocortin-1. Scattered or moderate numbers of cells exhibited lipocortin-1 immunoreactivity in the pars distalis of 89 subjects ranging in age from 27 weeks' gestation to 83 years. Seven immature and seven aged specimens exhibited no immunostaining, while 15 specimens from older individuals exhibited only rare immunostaining. Immunostaining did not appear to co-localize selectively with any specific pituitary hormone, although the distribution of immunoreactivity did overlap that of some corticotrophs and was seen in elongated processes of S-100-containing folliculostellate cells. Lipocortin-1 was also found in epithelial cells lining colloid cysts of the residual pars intermedia in 115 of 118 pituitaries ranging in age from 23 weeks' gestation to 83 years. In many intermediate lobe cysts, lipocortin-1 exhibited a pattern of immunoreactivity that partially overlapped the distribution of S-100 protein immunostaining, although the pattern was not identical. Pre-absorption of anti-lipocortin-1 antiserum with lipocortin-1-coupled Sepharose-4B immunoreactivity resulted in loss of immunoreactivity in both lobes. No lipocortin-1 immunoreactivity was seen in the neurohypophysis.

Adolescent↗
PubMed1990

Reversal of bupivacaine epidural anesthesia by intermittent epidural injections of crystalloid solutions.

This study was designed to determine whether epidural motor blockade could be reversed by postoperative injections of crystalloid solutions via the epidural catheter. Twenty-seven patients (ASA physical status I, nonlaboring) had epidural anesthesia with 0.75% bupivacaine for elective cesarean delivery. Postoperatively, patients were randomized to receive three 15-mL injections (over 30 min) of crystalloid solutions (normal saline or Ringer's lactate) or no treatment (control) via the epidural catheter. Degree of motor and sensory blockade was evaluated with an investigator blinded to treatment group. Rate of resolution of sensory blockade was not different among groups. However, time for resolution of motor blockade was more than twice as long in the control group than in either treatment group (control = 178 +/- 70 min vs Ringer's lactate = 84 +/- 44 min, normal saline = 70 +/- 38 min, P = 0.001). The data suggest that unwanted motor blockade due to epidural anesthesia can be reversed by epidural injections of crystalloid solutions.

Adult↗
PubMed1990

Role of calcium in adrenergic neurochemical transmission in the aging heart.

The effect of modification of extracellular Ca2+ concentration ([Ca2+]0), the administration of the neuronal Ca2+ channel blocker, omega-conotoxin, and the calcium (Ca2+) ionophore, ionomycin, were examined in the isolated heart of male Fisher-344 rats 6 and 24 months of age. Hearts with the right cardiac sympathetic nerve intact were isolated and perfused with Krebs-Ringer solution containing cocaine (10(-6) M) to block uptake 1, metanephrine (10(-6) M) to block uptake 2 and yohimbine (3 X 10(-6) M) to prevent alpha 2 receptor inhibition of Ca2+ influx. The nerve was stimulated with frequencies of 2, 6 and 12 Hz for 1 min and NE output was determined by high-performance liquid chromatography/electrochemical methods. Effluent of hearts from 6-month-old rats contained higher levels of NE than effluent of hearts from 24-month-old rats at all frequencies of stimulation when perfused with either normal (1.2 mM), low (0.3 mM) or high (4.8 mM) [Ca2+]0. Even when high [Ca2+]0 was used to make more Ca2+ available, the amount of NE in the effluent of 24-month-old animal hearts was only approximately 54% of that found in the effluent of 6-month-old animal hearts perfused with normal [Ca2+]0. omega-Conotoxin caused a greater decrease in NE release in the older preparations suggesting that the neuronal Ca2+ channels of older preparations are more susceptible to blockade than those of younger preparations.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗
PubMed1989

Congenital smooth muscle hamartoma. A report of six cases and a review of the literature.

Congenital smooth muscle hamartoma (CSMH) represents a proliferation of randomly oriented dermal smooth-muscle bundles. Six patients with CSMH were observed, the largest series to date, and the literature was reviewed. Congenital smooth muscle hamartoma has presented as congenital patches or slightly indurated plaques with prominent overlying hair (88% of cases), or rarely as patches with perifollicular papules without prominent hair (12% of cases). Most lesions (61% of cases) have been somewhat hyperpigmented, but 39% of cases have been flesh colored. Congenital smooth muscle hamartoma has occurred on the torso and proximal extremities, except for one case on the eyebrow and eyelid (present study). A positive pseudo-Darier's sign (temporary induration or piloerection after rubbing) helped to differentiate CSMH from congenital hairy nevo-cellular nevus. Congenital smooth muscle hamartoma is a distinct entity that is at one end of a spectrum that includes Becker's nevus, and should be considered in the differential diagnosis of any congenital hairy lesion.

Biopsy↗
PubMed1989

Intraspinal opioids: implications for monitoring. Monitoring in the intensive care unit is essential.

Patients receiving intraspinal opiates should be monitored in the intensive care unit for at least 24 hours to prevent potentially lethal outcomes. These include respiratory depression caused by sequestration of the morphine in the cerebrospinal fluid and migration of epidural catheters in the subarachnoid or intravascular space. At this time, most hospitals are not equipped or staffed adequately to guarantee the safety of these patients outside the intensive care unit.

Analgesics, Opioid↗
PubMed1989

Molecular scanning of Yq11 (interval 6) in men with Sertoli-cell-only syndrome.

Data suggesting that probes pDP105/B and 50f2/C,E may identify sequences on distal Yq11 (interval 6) that are critical for spermatogenesis stimulated a study of this region by means of these two probes in azoospermic 46,XY men with biopsy-proved Sertoli-cell-only syndrome. Deoxyribonucleic acid samples from controls and study subjects were digested with the restriction enzymes TaqI, EcoRI, and BamHI. These samples were blotted and hybridized with pDP105/B, 50f2/C,E, and two more proximal Yq11 probes 4B-2 and pAS1. The sequence hydridizing to 50f2/C was absent in one study subject. No deletions were detected with pDP105/B and the two more proximal probes.

Adult↗
PubMed1989

Regulation of progesterone receptor mRNA by oestradiol and antioestrogens in breast cancer cell lines.

The induction of progesterone receptor mRNA by oestradiol and antioestrogens has been characterised in the MCF-7 breast cancer cell line. Progesterone receptor mRNA was induced more than 100-fold by oestradiol. The induction was half-maximal in the presence of 10(-10) M oestradiol and maximum levels were reached after 24 h treatment. Progesterone receptor mRNA was induced to 10% of the oestrogen-induced level by tamoxifen and its metabolite 4'-hydroxytamoxifen. The increase was half-maximal in the presence of 5 X 10(-8) M tamoxifen or 5 X 10(-10) M 4'-hydroxytamoxifen. In contrast, neither the benzothiophene antioestrogen LY117018 nor the 7 alpha-alkyl steroidal antioestrogen ICI 164,384 had any effect on progesterone receptor mRNA. The progesterone receptor mRNA was also induced by oestrogen in a T47D subline and in two other oestrogen-responsive breast cancer cell lines (ZR-75, EFM-19). Tamoxifen was a partial oestrogen for progesterone receptor mRNA induction in each of these cell lines. The large induction of the progesterone receptor mRNA by oestrogen in all 4 breast cancer cell lines supports the contention that the progesterone receptor may be a good predictive marker of hormonal response in human breast cancer.

Animals↗
PubMed1989

Lipocortin-1 immunoreactivity in central and peripheral nervous system glial tumors.

We examined the cellular distribution of lipocortin-1 (L-1), a major physiologic substrate for the epidermal growth factor receptor/kinase, in 122 central nervous system (CNS) and peripheral nervous system (PNS) neoplasms using the peroxidase-antiperoxidase technique with a polyclonal antibody specific for L-1. Extensive L-1 immunoreactivity was demonstrated in many CNS tumors; in 11 of 21 glioblastoma multiformes, in five of 12 anaplastic astrocytomas, and in five of 14 astrocytomas. Significant numbers of immunoreactive ependymocytes or astrocytes were also seen in six of 13 ependymomas. In contrast, no immunostaining was detected in the oligodendrocytes in any of ten oligodendrogliomas. PNS tumors, found in two of five malignant nerve sheath tumors, 13 of 15 schwannomas, 13 of 17 neurofibromas, and 14 of 15 traumatic neuromas, also contained considerable L-1 immunoreactivity in Schwann cells or mast cells. These findings raise the possibility that L-1 may participate in the proliferation or subsequent differentiation of neoplastic astrocytes, ependymocytes, and Schwann cells.

Annexins↗
PubMed1989

Fetal surgery and general anesthesia: a case report and review.

Fetal surgery, in utero, is now a viable option for some congenital conditions due to recent advances in ultrasound and microsurgical technology. Previous reports of anesthesia for such procedures have focused on spinal or epidural conduction techniques. General endotracheal anesthesia may have several advantages in this setting. In addition to maternal anesthesia, general anesthesia can provide fetal neuromuscular block (without direct fetal injection of blocking agents) and uterine relaxation. It may also blunt fetal response to surgical stimulation.

Adult↗