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Biomedical subjects

A Harris

Publications and source records attributed to A Harris.

At least 217 records · Page 12Linked to original sources
PubMed1997

Is biliary lithogenesis affected by length and implantation of cystic duct? Study of 270 patients with endoscopic retrograde cholangiopancreatography.

The gallbladder seems to play an important role in lithogenesis. Moreover, the morphology and the implantation of the cystic duct may also influence this process. Our purpose was to evaluate if the length and the implantation of the cystic duct may affect the formation of gallstones. Between April 1992 and March 1994, 270 patients who underwent endoscopic retrograde cholangiopancreatography were included in the study, and the radiological length of the cystic duct was carefully recorded. Patients were divided into two groups: I, absence of lithiasis: 113 patients (65 men, 48 women); and II, gallbladder lithiasis or lithiasis in the common bile duct with or without gallbladder lithiasis: 157 patients (73 men, 84 women). A statistically significant difference was observed among the two groups regarding the insertion of the cystic duct: implantation on the left side of the common bile duct represented a risk factor of lithiasis. The length of the cystic duct was not directly implicated. Hypokinesis of the gallbladder is currently recognized as being a major factor in the initial steps of lithogenesis, but the implantation of the cystic duct can play an important role by increasing cystic duct resistance and causing a reduced washout effect of the gallbladder contents, including cholesterol crystals.

Adult↗
PubMed1997

Maturation decreases ethanol minimum alveolar anesthetic concentration in mice as previously demonstrated in rats: there is no species difference.

The potency of conventional inhaled anesthetics increases with maturation: the 50% effective dose (minimum alveolar anesthetic concentration [MAC]) for conventional inhaled anesthetics in the neonatal rat or human exceeds MAC in the young adult. This increase also applies to ethanol in rats tested using MAC as the measure of anesthesia. However, the converse appears to be true for studies in mice assessed with the righting reflex; that is, adult mice are six times more resistant than neonates to the effects of ethanol. These disparate findings imply that maturation in rats and mice may produce opposing changes in the quantity or sensitivity of one or more receptors that mediate the actions of anesthetics that lead to the anesthetic state. Such a finding would be important for two reasons. First, both rodents are widely used in studies of anesthetic effects, and, thus, a species-dependent divergence in anesthetic effects has immediate experimental implications. Second, confirmation of such a species difference would supply an opportunity to test which receptors might be crucial to anesthetic mechanisms. Accordingly, we investigated whether maturation decreased ethanol potency in mice, using MAC as the measure of anesthesia. Applying standard techniques, we tested MAC for ethanol in 15 CF-1 mice aged 10 days (6-8.5 g) and in 13 mice aged 77-84 days (34-39 g). MAC decreased with maturation, and the decrease was indistinguishable from that found in our previous studies of rats.

Aging↗
PubMed1997

Altered retrobulbar vascular reactivity in early diabetic retinopathy.

AIM/BACKGROUND: In diabetic eye disease the factors leading to compromised circulation and the resulting loss of visual function are poorly understood. Although retinal circulation has been widely investigated, it accounts for only a fraction of total eye blood flow. Blood flow was investigated in the larger vessels feeding the eye in patients with early diabetic retinopathy. METHODS: Eleven patients with early diabetes with minimal or no retinopathy and 11 healthy controls were evaluated for retrobulbar blood flow velocity using colour Doppler imaging for the ophthalmic and central retinal arteries. Patients and subjects were tested while breathing room air and again under conditions of isocapnic hyperoxia. RESULTS: Hyperoxia induced a significant change in the central retinal artery end diastolic velocity (EDV) (p = 0.008) and resistance index (RI) (p = 0.032) in normal subjects, but not in diabetic patients. Consequently, during hyperoxia, the diabetic patients were significantly higher for EDV (p = 0.006) and significantly lower for RI (p = 0.002) compared with normal controls. Hyperoxia caused no significant change in either group in the ophthalmic artery; nevertheless, under isocapnic hyperoxia conditions the diabetic patients had lower peak systolic velocity (p = 0.05) and lower RI (p = 0.05) than normal subjects. CONCLUSIONS: Imposition of isocapnic hyperoxia produces significant differences in the ophthalmic and central retinal artery blood flow velocities in diabetic patients with early disease when compared with normal subjects. These results demonstrate that diabetic patients with minimal or no retinopathy suffer from irregular ocular vascular function in the major vessels feeding the eye.

Adult↗
PubMed1997

Consent to treatment by minors attending accident and emergency departments: guidelines.

The absolute right to refuse medical treatment, even if the reasons are irrational, is confined to competent adults. Children under 16 years can give legal consent to treatment in the absence of consent from those with parental responsibility. Children under 18 years do not, however, have an absolute right to consent, or refuse to consent, to treatment. The views of children assume increasing importance with age and maturity. Accident and emergency medical and nursing staff may face difficult decisions when children, or those with parental responsibility, refuse to consent to medical treatment. This paper presents guidelines designed to guide the decision making process in immediately or potentially life threatening conditions and in non-life-threatening conditions.

Adolescent↗
PubMed1997

Developmental expression of mucin genes in the human respiratory tract.

Mucin glycoproteins play a key role in the normal function of the airway epithelium. We examined the expression of mucin genes, MUC3, 4, 5AC, 5B, 6, 7, and 8 in human fetal tissues to establish the localization and age of onset of expression of each mucin gene during human development. We detected expression of MUC4, 5AC, 5B, and 7 in the mid-trimester airway epithelium but did not detect expression of MUC3, 6, or 8. MUC4 was expressed in the trachea and large airways in the majority of cells in the airway epithelium. Expression of MUC5AC was only seen in individual goblet cells in the trachea, while MUC5B was expressed in the surface epithelium of the trachea at 13 wk but was largely restricted to submucosal glands by 23 wk of gestation.

Base Sequence↗
PubMed1997

The desensitization of oxytocin receptors in human myometrial cells is accompanied by down-regulation of oxytocin receptor messenger RNA.

We have recently provided evidence for the desensitization of oxytocin receptors in human myometrial cells. In the present study, we have investigated the possible mechanisms by which oxytocin (OT) might regulate OT receptor density. The steady state level of OT binding in cultured myometrial cells was 220 x 10(3) binding sites/ cell, but this was time-dependently reduced to 27 x 10(3) sites/cell by exposure to OT for up to 20 h. Similarly, OT exposure decreased the binding of OT to cell membranes. In contrast, Western blotting data showed that the total amount of OT receptor protein was not affected by OT treatment for up to 48 h. Flow cytometry experiments demonstrated that OT receptors are not internalized during prolonged exposure of the cells to OT. However, RNase protection assays and Northern analysis showed that OT receptor mRNA was reduced by OT treatment to reach a new low steady state level with a time course similar to that of the disappearance of cell surface OT binding sites. Possible mechanisms involved in mRNA down-regulation include transcriptional suppression and destabilization of mRNA by RNA binding proteins.

Blotting, Northern↗
PubMed1997

Solar urticaria in an infant.

A 2-year-old girl presented with a history of an erythematous rash which occurred immediately after exposure to sunlight and had been a problem since birth. Extensive laboratory investigations to exclude genophotodermatoses, photosensitivity secondary to metabolic disorders and photoaggravated dermatoses were negative. Monochromator irradiation phototesting demonstrated immediate erythematous flares to all ultraviolet B (UVB), UVA and visible wavelengths up to 500 nm. A diagnosis of solar urticaria was made and she responded to loratidine 10 mg daily. We believe this is the first report of solar urticaria, confirmed by phototesting with a monochromator so early in life.

Child, Preschool↗
PubMed1997

Nocturnal ophthalmic arterial hemodynamics in primary open-angle glaucoma.

PURPOSE: Recent studies have found nocturnal reductions in systemic arterial blood pressure associated with progressive visual field loss in glaucoma. Although ocular ischemia has been hypothesized to link these two phenomena, it remains unknown if perfusion of the eye is reduced during the night in patients with glaucoma. PATIENTS AND METHODS: Nine patients with primary open-angle glaucoma (POAG) and stable visual fields who were free from systemic hypertension, as well as nine age- and gender-matched controls, were studied at 9:00 P.M., and then during sleep at 12:00, 3:00, and 6:00 A.M. Systemic blood pressure, intraocular pressure (IOP), and color Doppler imaging (CDI) of the ophthalmic artery were measured at each time. RESULTS: Arterial blood pressure and ophthalmic artery peak systolic and end-diastolic velocities were similar and were unchanged over time, in both groups. In contrast, the ophthalmic arterial resistance index decreased as the night progressed (p < 0.05), identically in controls and patients. In patients with glaucoma, CDI indices were independent of changes in arterial pressure, IOP, or calculated ocular perfusion pressure. CONCLUSION: Patients with POAG characterized by stable visual fields who were free from systemic hypertension exhibited normal ophthalmic arterial hemodynamics at night; there was no evidence of ocular ischemia or vasoconstriction.

Blood Pressure↗
PubMed1997

Cystic fibrosis of the pancreas: involvement of MUC6 mucin in obstruction of pancreatic ducts.

BACKGROUND: Cystic fibrosis (CF) is characterized by pancreatic destruction following the gradual obstruction of small pancreatic ducts, from the mid-trimester of gestation onwards. To date, the material causing the obstruction has not been identified. The MUC6 mucin cDNA was isolated from human stomach and has been shown to be expressed in a number of other tissues in the gastrointestinal tract, including the gall bladder and parts of the ileum and colon. MATERIALS AND METHODS: We have examined the expression of MUC6 mucin in the human pancreas, both during development and postnatally, by mRNA in situ hybridization and immunocytochemistry. RESULTS: In this report we establish that MUC6 transcripts are abundant in pancreatic epithelial cells and show a very similar pattern of expression in the epithelium lining small ducts and centroacinar cells to that shown by the cystic fibrosis transmembrane conductance regulator gene (CFTR). In addition, material obstructing the pancreatic ducts of CF pancreas was shown to contain MUC6 mucin. CONCLUSION: We have identified MUC6 mucin as a significant constituent of the material obstructing the small pancreatic ducts in CF.

Adolescent↗
PubMed1997

A color Doppler analysis of nifedipine-induced posterior ocular blood flow changes in open-angle glaucoma.

PURPOSE: This pilot study used color Doppler imaging to investigate the effects of nifedipine on the posterior ocular blood flow of patients with glaucoma progression at normal intraocular pressures. PATIENTS AND METHODS: Eighteen patients, 11 men and seven women with a median age of 61.7 years, were imaged before and 6 weeks after the initiation of 30 mg of sustained-release nifedipine (Procardia XL; produced by either Pfizer or Pratt) daily. RESULTS: There was no statistically significant change in the blood velocity of the ophthalmic artery, central retinal artery, and main nasal and temporal short posterior ciliary arteries after treatment with nifedipine. CONCLUSION: The routine use of nifedipine in patients with normal tension glaucoma progression is not supported by this study.

Adult↗
PubMed1997

Contrast sensitivity loss is coupled with capillary dropout in patients with diabetes.

PURPOSE: To assess the relationship of foveal microcirculation to contrast sensitivity function in early diabetes mellitus. METHODS: Twenty patients with diabetes with visual acuity of 20/25 or better without clinically significant macular edema were evaluated. Measurements of contrast sensitivity at four spatial frequencies (3, 6, 12, and 18 cycles/degree [c/deg]), macular capillary blood velocity (CBV), capillary density (PIA: perifoveal intercapillary area), foveal avascular zone (FAZ), and microaneurysm count were performed. Contrast sensitivity data collected from age-matched normal subjects and previously published normal angiographic data were used for comparison with our cohort with diabetes. RESULTS: The CBV was significantly reduced (P < 0.0001) and PIA and FAZ were significantly enlarged (P < 0.0001) when compared with healthy subjects. Contrast sensitivity was significantly lower in the group with diabetes at 6 (P = 0.01) and 12 (P = 0.002) c/deg as compared with healthy control values. FAZ and PIA correlated significantly (FAZ; r = -0.60, P = 0.005; PIA; r = -0.54, P = 0.02) with contrast sensitivity at 12 c/deg. CONCLUSIONS: The alterations of the perifoveal network are related to selective disturbances of central visual function as measured by contrast sensitivity. In patients with diabetes measurement of contrast sensitivity may provide a clinical adjunct in further identifying early ischemic diabetic maculopathy.

Adult↗
PubMed1997

Color Doppler ultrasound measurements after topical and retrobulbar epinephrine in primate eyes.

PURPOSE: To determine the effects of topical epinephrine and retrobulbar anesthesia containing lidocaine with epinephrine on retrobulbar hemodynamic measurements in the primate eye, using color Doppler ultrasound. METHODS: Color Doppler ultrasound measurements were performed at baseline and 90 minutes after masked administration of topical 2% epinephrine or balanced salt solution to six cynomolgus monkeys. Measurements were also performed at baseline and 30 minutes after retrobulbar injection of 2% lidocaine, with or without 1:200,000 epinephrine. RESULTS: After topical epinephrine, color Doppler ultrasound measurements were not significantly different compared with baseline measurements in the central retinal artery, posterior ciliary arteries, and superior ophthalmic vein. There were decreased systolic and diastolic velocities in the ophthalmic artery (P < 0.03 and P < 0.02, respectively) after topical epinephrine; however, Pourcelot's ratio (resistive index) was not significantly different compared with that at baseline. In contrast, there were marked changes in the retrobulbar arterial circulation after retrobulbar injection of lidocaine with epinephrine. The systolic and diastolic velocities were decreased significantly in the central retinal artery (P < 0.02 and P < 0.01, respectively), temporal posterior ciliary artery (P < 0.05 and P < 0.03, respectively), and nasal posterior ciliary artery (P < 0.03 and P < 0.02, respectively). Pourcelot's ratio was significantly increased in the central retinal artery (P < 0.01), temporal posterior ciliary artery (P < 0.02), and nasal posterior ciliary artery (P < 0.02) after retrobulbar injection of lidocaine with epinephrine. CONCLUSIONS: These results indicate that one drop of topical epinephrine has little or no effect on the retrobulbar circulation, whereas retrobulbar injection of anesthetic solution containing lidocaine with epinephrine significantly alters retrobulbar hemodynamics in the monkey eye.

Administration, Topical↗