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Biomedical subjects

S Holland

Publications and source records attributed to S Holland.

At least 73 records · Page 4Linked to original sources
PubMed1992

Hb Rancho Mirage [beta 143(H21)His----Asp]; a variant in the 2,3-DPG binding site showing normal oxygen affinity at physiological pH.

Hb Rancho Mirage was detected in a 17-year-old male in association with a mild anemia. Hemoglobin electrophoresis revealed the variant had a mobility between Hbs A and J on cellulose acetate (pH 8.6) and a mobility like Hb F on citrate agar (pH 6.4). A substitution of His----Asp was found at position 143 in the beta chain, a residue that contributes to the anionic 2,3-DPG binding site in Hb. This variant exhibited normal oxygen affinity at physiologic pH and reduced affinity at alkaline pH. This suggested a subtle shift in the allosteric equilibrium due most likely to the introduction of a negative charge that stabilized the 2,3-DPG pocket. Both homotrophic (heme-heme) and heterotropic (2,3-DPG and protons) effects were reduced; this might be a consequence of an alteration in the carboxyl terminal region of the beta-subunits. Although a His----Asp substitution would be considered to cause reasonable disruption of the 2,3-DPG and C-terminal conformation of the beta- subunits, the properties of Hb Rancho Mirage suggest that, in fact, there appear to be no major perturbation of the critical C-terminal residues.

2,3-Diphosphoglycerate↗
PubMed1992

Violence. Upping the ante. Interview by Cath Jackson.

Handling a physical attack is 'just the tip of the volcano' says Stevie Holland, author of a radical new distance learning pack on 'Managing aggression' at work. Health visitors, school nurses and their managers need training in preventive strategies to defuse potentially violent situations. They should also be looking at their own attitudes to colleagues and clients and at the culture of the organisation within which they work.

Attitude of Health Personnel↗
PubMed1991

Fulminant pseudomonal keratitis and scleritis in human immunodeficiency virus-infected patients.

Patients with human immunodeficiency virus infection are predisposed to fungal, parasitic, and viral infections. Bacterial infection can also be seen, although ocular bacterial infections have not been reported in patients with acquired immunodeficiency syndrome until recently. We present two cases of Pseudomonas corneoscleritis and one case of Pseudomonas keratitis in patients with human immunodeficiency virus infection that failed to respond to antibiotic treatment. Predisposing factors included extended-wear soft contact lens use in one patient and exposure secondary to Bell's palsy in another patient. All three patients had neutropenia that may have contributed to their poor response to treatment. Enucleation was required to treat two patients with overwhelming infection. Enucleation has been rarely required for treatment of corneoscleritis in immunocompetent patients treated at our institution. Pseudomonas keratitis in human immunodeficiency virus-infected patients represents a serious ocular infection requiring early diagnosis and aggressive treatment.

Acquired Immunodeficiency Syndrome↗
PubMed1991

Cytochemically detectable glucose-6-phosphate dehydrogenase-stimulating/Na-K-ATPase-inhibiting activity of plasma and hypothalamus in reduced renal mass hypertension.

Plasma from normal humans and rats on a high sodium intake, and from patients and rats suffering from hereditary hypertension has an increased cytochemically detectable glucose-6-phosphate dehydrogenase (G6PD)-stimulating/Na-K-ATPase inhibiting activity. The hypothalamic content of this activity is also increased by a high sodium intake and in the spontaneously hypertensive rat (SHR). Using cytochemical techniques, the ability of plasma and the hypothalamus of reduced renal mass hypertensive rats to stimulate G6PD activity and to inhibit Na-K-ATPase was measured. The mean G6PD-stimulating capacity of the plasma from the hypertensive and normotensive groups of rats was 351 +/- 67 and 11.42 +/- 1.98 G6PD-stimulating units/mL respectively (P less than .001). The time courses of the ability of plasma from a hypertensive and a normotensive rat to inhibit fresh tissue Na-K-ATPase after 2, 4, 6, and 8 min of exposure demonstrated that the hypertensive rat plasma had a greater capacity to inhibit Na-K-ATPase. The mean G6PD-stimulating capacity of the hypothalamus from the hypertensive and normotensive groups of rats was 252,263 +/- 147,958 X 10(3) and 6.38 +/- 2.35 X 10(3) G6PD-stimulating units per hypothalamus, respectively (P less than .01). It is proposed that the raised concentration of cytochemically detectable G6PD-stimulating/Na-K-ATPase-inhibiting substance in both genetic and nongenetic forms of hypertension may be a manifestation of a communal hypertensinogenic mechanism. Thus, the raised plasma concentration would have a direct peripheral vascular constricting effect and the high hypothalamic concentration would be responsible for a central nervous hypertensinogenic effect.

Animals↗
PubMed1991

The Children Act 1989: the professional dilemma of advocacy.

Stevie Holland looks at the background to the Children Act 1989 and argues that there is a contradiction between the Act's commitment to the welfare of the child and its policy of non-intervention in family life. Although written as a speech for this year's HVA annual professional conference, owing to illness it was not delivered at the conference.

Child↗
PubMed1990

Topical anesthetic abuse.

Topical ocular anesthetic abuse is a serious disorder causing keratitis and persistent epithelial defects. It may be the result of either prescription by the patient's eye care practitioner, theft from the practitioner's office, or occult additives in therapeutic medications. The authors report observations of six individuals suffering from this disorder which suggest that persistent epithelial defects, corneal stromal ring infiltrates, disproportionate pain, and prescription or nonprescription substance abuse may be factors involved. Penetrating keratoplasty was required to treat corneal perforation in two patients, and permanent corneal structural damage was noted in two eyes. Two eyes had a relentless downhill course culminating in enucleation. Because five of the six patients were diagnosed and treated as having presumed Acanthamoeba keratitis during the course of their disease, topical ocular anesthetic use should be included in the differential diagnosis of chronic keratitis and may masquerade as Acanthamoeba keratitis. The authors believe that practitioners should not prescribe or dispense topical anesthetics and should avoid clinical settings which provide an opportunity for the theft of topical ocular anesthetics.

Acanthamoeba Keratitis↗
PubMed1990

The ocular manifestations of syphilis in the human immunodeficiency virus type 1-infected host.

Nine patients with active ocular or optic nerve involvement by syphilis who also had concurrent human immunodeficiency virus type-1 (HIV-1) infection are described. The ocular manifestations of syphilis led to the discovery of HIV-1 seropositivity in four of nine cases. Fifteen eyes were affected. Ocular manifestations were: iridocyclitis in three eyes, vitreitis in one eye, retinitis or neuroretinitis in five eyes, papillitis in two eyes, optic perineuritis in two eyes, and retrobulbar optic neuritis in two eyes. Three patients diagnosed with acquired immune deficiency syndrome (AIDS) had the worst initial visual acuities. Six of nine patients had evidence of concomitant central nervous syndrome (CNS) involvement with syphilis. Benzathine penicillin was administered intramuscularly to three patients. All three had relapses. Seven of nine patients treated intravenously with high-dose penicillin had dramatic responses to therapy with improvement in vision and serologies and no evidence of relapse. Regimens accepted for the treatment of neurosyphilis appear to be adequate for the treatment of ocular syphilis in HIV-1-infected patients though further long-term follow-up will be required.

Adult↗
PubMed1990

Doppler US. Part I. Basic principles, instrumentation, and pitfalls.

This article reviews some of the important physical principles involved in Doppler ultrasound (US) in the context of modern diagnostic US technology. Methods of quantitative Doppler US data analysis used to distinguish normal hemodynamics from disturbed flow conditions are discussed with the aid of numerous examples. Definitions and measurement techniques are presented for determining from Doppler signals such indicators of arterial disease as velocity, volume flow rate, flow impedance, and pulsatility. Spectral analysis and its utility in Doppler signal analysis are described. The various options available on modern Doppler US instrumentation are reviewed, including duplex Doppler techniques and color Doppler flow mapping. Finally, the authors discuss artifacts and pitfalls likely to be encountered in the routine clinical use of Doppler US for diagnostic purposes.

Doppler Effect↗
PubMed1990

Distance learning: the HVA project's pilot stage.

The second article in this series described the origination, aims and early development of distance learning material to help both health visitors who were returning to practice after a number of years, and also those who had stayed in practice but who had little access to courses to update themselves professionally.

Community Health Nursing↗
PubMed1989

Management options for Propionibacterium acnes endophthalmitis.

The authors reviewed the management of nine culture-proven cases of Propionibacterium acnes endophthalmitis which presented at an average of 4 months after extracapsular cataract extraction (ECCE) and posterior chamber intraocular lens (PC IOL) implantation. The initial signs included a white intracapsular plaque (9/9), vitritis (9/9), granulomatous uveitis (4/9), nongranulomatous uveitis (5/9), hypopyon (4/9), beaded fibrin strands in the anterior chamber (3/9), and diffuse intraretinal hemorrhages (2/9). A variety of management schemes were used in these patients, including the following: topical and intravenous antibiotics alone; intraocular and topical antibiotic administration; pars plana vitrectomy with capsulectomy and intraocular antibiotic administration; and removal of all capsular remnants with PC IOL removal or exchange. The final visual acuities ranged from 20/20 to 20/60 in six eyes and 20/200 to 20/400 in three eyes. This review suggests that a variety of management options for P. acnes endophthalmitis appear to be successful. Based on the authors' experience, an algorithm for future treatment is offered.

Aged↗
PubMed1989

Potential use of lasers for penetrating keratoplasty.

Experimental corneal trephination has been achieved with the 193 nm argon fluoride excimer and 2.9 microns hydrogen fluoride and Er:YAG laser systems. Compared with metal blades and other lasers, the 193 nm excimer laser creates the best quality corneal excision, but has a relatively slow etch rate through the stroma, and its use requires toxic gas. The mid-infrared laser systems trephine the cornea in less than 10 seconds, but cause a 10 microns to 15 microns zone of adjacent stromal damage and create wounds that are approximately 2.5 times larger than wounds made by metal scalpels. The wavelength and laser pulse duration influence the cutting characteristics of the laser. Optical delivery systems using an axicon lens, a rotating slit, and a computer controlled scanning optical system have been developed for penetrating keratoplasty. Selection of the optimal laser system for penetrating keratoplasty must await further experimental studies. Refinements of the laser cavity and delivery system are necessary before clinical studies can begin. A carefully controlled randomized clinical trial comparing laser trephination with conventional mechanical trephines will be necessary to determine the safety and efficacy of a laser trephination system.

Cornea↗
PubMed1989

Modeling sickle cell vasoocclusion in the rat leg: quantification of trapped sickle cells and correlation with 31P metabolic and 1H magnetic resonance imaging changes.

We have developed an animal model to elucidate the acute effects of perfusion abnormalities on muscle metabolism induced by different density-defined classes of erythrocytes isolated from sickle cell anemia patients. Technetium-99m (99mTc)-labeled, saline-washed normal (AA), homozygous sickle (SS), or high-density SS (SS4) erythrocytes were injected into the femoral artery of the rat and quantitative 99mTc imaging, 31P magnetic resonance spectroscopy by surface coil at 2 teslas, and 1H magnetic resonance imaging at 0.15 tesla were performed. Between 5 and 25 microliters of SS4 cells was trapped in the microcirculation of the thigh (or 1-6 x 10(7) cells per cubic centimeter of tissue). In contrast, fewer SS discocytes (SS2) or AA cells were trapped (an equivalent packed cell volume of less than 6.7 microliters and 0.3 microliters, respectively). After injection of SS4 cells an initial increase in inorganic phosphate was observed in the region of the thigh served by the femoral artery, intracellular pH decreased, and subsequently the proton relaxation time T1 reached a broad maximum at 18-28 hr. When T1 obtained at this time was plotted against the volume of cells trapped, an increase of T1 over the control value of 411 +/- 48 msec was found that was proportional to the number of cells trapped. We conclude that the densest SS cells are most effective at producing vasoocclusion. The extent of the change detected by 1H magnetic resonance imaging is dependent on the amount of cells trapped in the microcirculation and the magnitude of the initial increase of inorganic phosphate.

Anemia, Sickle Cell↗
PubMed1989

Studies on phagocytosis in patients with acute bacterial infections.

Polymorphonuclear leukocytes (PMN) and monocytes from 20 patients with acute bacterial infections were examined for phagocytic function. PMN of patients expressed markedly enhanced phagocytosis as measured by the ingestion of erythrocyte (E)IgG and IgG/C3b-coated E. Phagocytosis of E coated with C3b alone was not seen, while low levels of ingestion of iC3b-E by patients' PMNs was noted. Monocytes from patients and controls expressed similar phagocytic activity in a fixed endpoint assay; however, the kinetics of phagocytosis by patients' monocytes was strikingly faster. Superoxide anion (O2.) and myeloperoxidase activities were similar to controls in PMN of four patients studied on day 1 of admission. PMN from two of three patients studied longitudinally showed an initial elevation in EIgG phagocytosis, which fell to normal levels by day 4, concomitantly with increased O2. generation and clinical improvement. Phagocytosis remained elevated in the third patient who did not clear his septicemia. Surface membrane FcRII, FcRIII, CR1, and CR3 were similar on patient and control PMN. In contrast, FcRI was increased on PMN of five of seven patients by monomeric IgG binding, and on two of two patients by monoclonal anti-FcRI binding. Thus, PMN and monocytes of patients with acute bacterial infections are either upregulated with regard to phagocytic function or are less susceptible to downregulation than are normal cells. This presumably would have a beneficial effect on host defenses during infection.

Adult↗
PubMed1989

Shadow photogrammetric apparatus for the quantitative evaluation of corneal buttons.

We have developed a technique for the accurate, quantitative, geometric evaluation of trephined and punched corneal buttons. A magnified shadow of the frontal and edge views of a corneal button mounted on the rotary stage of a modified optical comparator is projected onto the screen of the comparator and photographed. This process takes approximately three minutes. The diameters and edge profile at any meridian photographed can subsequently be analyzed from the film. The precision in measuring the diameters of well cut corneal buttons is +/- 23 microns, and in measuring the angle of the edge profile is +/- 1 degree. Statistical analysis of inter observer variability indicated excellent reproducibility of measurements. Shadow photogrammetry offers a standardized, accurate, and reproducible method for analysis of corneal trephination.

Calibration↗