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Biomedical subjects

D Archer

Publications and source records attributed to D Archer.

At least 55 records · Page 3Linked to original sources
PubMed1992

Branch retinal vein occlusion and its management.

The natural course of Branch Retinal Vein Occlusion is determined by the site and completeness of the occlusion, the integrity of arterial perfusion to the affected sector and the efficiency of the developing collateral circulation. Most patients with tributary vein occlusion have some capillary fall out and microvascular incompetence in the distribution of the affected retina and vision is significantly compromised in over 50% of patients who have either chronic macular oedema or ischemia involving the perifoveolar arcades. Retinal and capillary vasoproliferation with or without intraretinal or preretinal membrane formation are common sequelae, where inner retinal ischemia is extensive and vitreous hemorrhage is often a distinct threat to vision. Treatment of the sequelae of vein occlusion are largely centered on laser photocoagulation to diseased retina to limit fluid accumulation and abolish preretinal and papillary neovascularization. Vitrectomy and retinal detachment procedures are occasionally required in patients with uncontrolled vitreous hemorrhage and retinal membrane formation which threatens the integrity of the macula. A small proportion of patients with vein occlusion subsequent to vasculitis require medical therapy.

Edema↗
PubMed1992

Call me Doc.

The bright lights of the big city hold no attraction for these two rural Iowa family physicians. The true rewards, they say, can be found in a small town medical practice.

Family Practice↗
PubMed1992

Duodenal duplication cysts: case report and review of the current literature.

Duodenal duplication cysts constitute a rare congenital anomaly of the gastrointestinal system, and a preoperative diagnosis of the condition is even less common. The authors present a case of a duodenal duplication cyst in a 3-year-old child in whom they were able to make the correct diagnosis preoperatively by means of ultrasonography and computed tomography.

Child, Preschool↗
PubMed1991

[Primary malignant melanoma of the oral cavity: a case report and review].

The oral cavity is a rare location for the development of primary malignant melanoma. Two cases of malignant melanoma of the superior alveolar process are described. The necessity of an early recognition and of clarification concerning the differential diagnosis of oral pigmentation as well as the treatment are discussed, together with a review of the literature.

Adult↗
PubMed1988

Changes in CSF pressure after mannitol in patients with and without elevated CSF pressure.

In view of the current concern that rapid infusion of mannitol might initially aggravate intracranial hypertension, the effects of a mannitol infusion on lumbar cerebrospinal fluid pressure (CSFP) were investigated in 49 patients. The studies were performed when the patients were under general anesthesia prior to elective craniotomy for tumor resection or intracerebral aneurysm clipping. The patients were divided into two groups: 24 patients with normal CSFP (Group I, mean CSFP 10.5 mm Hg) and 25 with raised CSFP (Group II, mean CSFP 20.8 mm Hg). Measurements of CSFP, mean arterial blood pressure (MABP), and central venous pressure (CVP) were made serially during and after the infusion of 20% mannitol (1 gm.kg-1 infused over a 10-minute interval). In both groups, mannitol infusion provoked a fall in MABP and an increase in CVP. An immediate decrease [corrected] in CSFP was observed in Group II, whereas CSFP increased transiently but significantly in Group I. Analysis of the arterial and venous driving pressures which contribute to CSFP suggests that the transient increase in CSFP after mannitol in Group I was partly due to the increase in CVP. The presence of intracranial hypertension may thus alter the CSFP response to arterial and venous pressure changes. Cerebral blood volume (CBV) was measured in dogs in a separate study analogous to the human protocol. The CBV increased approximately 25% over control values after mannitol infusion both in the normal animals and in those with CSFP raised by an epidural balloon. The response of the CSFP to mannitol infusion differed between both groups in a fashion similar to that observed in the human subjects. Thus, differences in CBV changes after mannitol do not account for the difference in CSFP response between normal subjects and those with raised CSFP.

Animals↗
PubMed1987

Permeability of the rat small intestine to carbohydrate probe molecules.

1. Absorption of carbohydrate probe molecules from ligated loops of rat small intestine was studied. Absorption was determined by measuring recovery of molecules in the urine, corrected for incomplete recovery after intravenous injection, and was examined for correlation with several parameters of molecular dimension. 2. Absorption depended on molecular volume rather than relative molecular mass, molecular radius or molecular area. 3. Molecules with a molecular volume below 225 X 10(-3) nm3 were absorbed to a greater extent than larger molecules, and absorption was affected critically by molecular volume, small changes in volume producing considerable variation in absorption. 4. Absorption of larger molecules was not affected by changes in volume within the range 362 X 10(-3)-1128 X 10(-3) nm3. 5. These findings support the concept that there are at least two aqueous diffusion pathways across the intestinal mucosa. small molecules diffusing through a small channel of finite dimension, compatible with a transcellular aqueous pore, whilst large molecules diffuse through a less frequent pathway of considerably larger dimensions.

Animals↗
PubMed1986

A physiological approach to surgery for acute rupture of the papillary muscle.

There is controversy regarding the optimal management of patients in whom acute papillary muscle rupture develops. This study evaluates the effect of division of the anterolateral papillary muscle on left ventricular (LV) function and compares two methods of treatment--mitral valve replacement (MVR) and mitral valve repair. Thirteen pigs were placed on cardiopulmonary bypass, and interventions were performed in an isolated beating heart preparation. LV function was assessed with a compliant intraventricular balloon at baseline, after division of the anterolateral papillary muscle (Divided), after repair of the divided papillary muscle (Repair), and finally after MVR. Division of the anterolateral papillary muscle caused a significant deterioration in LV function. Function was maintained at this level after mitral valve repair but deteriorated with MVR. Developed pressure measured at baseline was 179 +/- 13 mm Hg; Divided, 148 +/- 11 mm Hg (p less than 0.05 versus baseline); Repair, 149 +/- 15 mm Hg; and MVR, 95 +/- 8 mm Hg (p less than 0.05 versus Divided) at a balloon volume of 20 ml. These results suggest that LV function is impaired by papillary muscle rupture. Repair of the ruptured papillary muscle is associated with better LV function than is MVR.

Acute Disease↗
PubMed1984

Antibody responses to toxic-shock-syndrome (TSS) toxin by patients with TSS and by healthy staphylococcal carriers.

Serum samples taken from women with toxic-shock syndrome (TSS) and from women without a history of TSS were examined for the presence of antibodies to toxic-shock-syndrome toxin (TST). Serum samples from 38 women with TSS and from 70 women with no history of TSS were analyzed by radioimmunoassay (RIA) and by an enzyme-linked immunoadsorbent assay (ELISA). Antitoxin titers obtained by the assays were highly correlated. Antibody levels in sera of women with TSS, or a history of TSS, were significantly lower than levels in sera of women with no prior evidence of TSS. The mean level of antitoxin titers in the total sample of acute, convalescent, and recovered TSS groups was significantly lower than that of the control groups, which consisted of 31 carriers of genital Staphylococcus aureus and a similar number of age- and race-matched noncarriers. Although a trend toward elevated antitoxin titers was apparent after recovery, no vigorous immunologic response to TST was noted. In contrast, the majority of healthy women demonstrated measurable antitoxin titers, a finding indicative of current or prior colonization with TST-producing strains of S. aureus. The data suggest that absence of antibodies to the TSS toxin may be a predisposing factor in the development of clinical disease.

Antitoxins↗
PubMed1982

Antagonism of pancuronium in renal failure: no recurarization.

Neuromuscular transmission was measured using train-of-four stimulation, during and after anaesthesia, in 20 patients with end-stage renal failure. Neuromuscular blockade was provided with pancuronium in single doses of either 3 or 6 mg per 70 kg, and antagonized at 10% recovery with atropine and neostigmine 2.5 mg per 70 kg. Reversal was followed by progressive recovery of muscle twitch in every patient during the 3 h of the study. Recovery was more rapid after the smaller dose of pancuronium and was inversely correlated with the duration of blockade. It is concluded that, when pancuronium is antagonized with neostigmine in patients with renal failure, neuromuscular transmission recovers without evidence of recurarization. However, when large doses of pancuronium are antagonized with neostigmine 2.5 mg, recovery may be insufficient to ensure normal ventilatory function.

Adult↗
PubMed1980

A patterned macular dystrophy with yellow plaques and atrophic changes.

Three middle-aged male patients are described with a peculiar patterned dystrophy of the macula. The basic lesions are discrete yellow plaques typically confined to the macular area and radiating from the fovea. They appear to be located at the level of the retinal pigment epithelium (RPE). With the passage of time some of the yellow plaques altered in extent and configuration, and atrophic changes appeared or extended. Visual acuity and electrophysiological tests are either normal or only moderately affected. The lesions appear to be distinct from the patterned dystrophies of the retina already described and from other conditions characterised by yellow or white deposits at the level of the RPE.

Adult↗
PubMed1980

In vivo suppression and enhancement of the murine homocytotropic antibody response by staphylococcal enterotoxin A.

Effects of staphylococcal enterotoxin A (SEA) on the mouse homocytotropic antibody (HCA) system were studied. Groups of BDF mice received 10 micrograms SEA either orally or intraperitoneally at 0, 24, 48 h before or after immunization with 100 micrograms ovalbumin in 1 mg A1(OH)3 gel. Primary and secondary HCA responses were determined by 48-hour passive cutaneous anaphylactic reactions in genetically hairless mice. It was found that effects of SEA on HCA responses were dependent on the time and route of SEA administration. In general, early administration (48 h before immunization) of SEA showed suppression, while later administration (either 24 h before or after immunization) of SEA demonstrated enhancement. A further delay of SEA administration (48 h after immunization) exerted suppressive effects except when it was given intraperitoneally in the anamnestic HCA experiments. The mouse HCA system proved to be a suitable in vivo correlate of in vitro plaque-forming cell responses modulated by SEA.

Animals↗