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Biomedical subjects

G Fishman

Publications and source records attributed to G Fishman.

At least 19 recordsLinked to original sources
PubMed2005

Spin-induced forbidden evanescent states in III-V semiconductors.

Within the band gap of a semiconductor no electronic propagating states are allowed, but there exist evanescent states which govern charge transport such as tunneling. In this Letter, we address the issue of their spin dependence in III-V semiconductors. Taking into account the spin-orbit interaction, we treat the problem using a k . p 14 x 14 Hamiltonian that we numerically compute for GaAs. Our results show that the removed spin degeneracy in the band gap can lead to giant energy splittings and induces forbidden zones in space where evanescent states are suppressed.

Journal Article↗
PubMed2004

Autoantibody panel screening in recurrent miscarriages.

PROBLEM: Antiphospholipid autoantibodies (aPL), antithyroid antibodies and anti-extractable nuclear antigens (anti-ENA) have all been reported to be associated with recurrent miscarriages (RM) and infertility. However, this association remained controversial. MATERIALS AND METHODS: Fifty-eight women with impaired fertility (38 women with RM and 20 women with infertility, but no miscarriages) and 28 control parous women were screened for seven autoantibodies [antithyroglobulin (aTG), antithyroid peroxidase (aTPO), anticardiolipin (aCL), antiphosphatidyl-serine (aPS), antiprothrombin antibodies (aPT), anti-beta 2 glycoprotein 1 (abeta2GP1), and anti-ENA]. There was no evidence for autoimmune diseases in the patients or the control. The analysis was also performed with several panels of autoantibodies, each of which contained two or more autoantibodies. RESULTS: Anti-TPO was the only antibody to be associated with RM (P = 0.01). A significant association was found between RM, and autoantibodies in the 'aTG + aTPO + anti-ENA' or 'aTG + aTPO' panels. The 'aTG + aTPO + anti-ENA' panel was also associated with RM when the analysis was performed only on 17 women who had secondary infertility: 10 from the 38 women with RM, and seven from the 20 women with infertility and no miscarriages. A significant association (P < 0.001) was also apparent between anti-CL and anti-PS and infertility compared with the 28 control women. CONCLUSIONS: RM was associated with autoantibodies to aTPO and the combined panel of aTPO, aTG and anti-ENA, but not with aPL. aPL were associated with infertility.

Abortion, Habitual↗
PubMed2003

Improving children's cooperation with tracheotomy care by performing and caring for a tracheotomy in the child's doll-a case analysis.

Described is a 2-year-old child who required a tracheotomy for an obstructing laryngeal tumor. Post-operatively the child responded with extreme anxiety and refused to cooperate with tracheostomy care including suctioning, tie changing and cannula change. A novel approach was attempted. We performed a tracheotomy on the child's favorite doll and taught her to perform all the necessary tracheostomy care on the doll. Once the child became accustomed to treating the doll, it became much easier to care for her tracheostomy and compliance to treatment improved greatly to the point were restraint was no longer required. This model of mock surgery and care of a child's doll may be helpful in treating young children with tracheotomies.

Child, Preschool↗
PubMed2002

Long polaron lifetime in InAs/GaAs self-assembled quantum dots.

We have investigated the polaron dynamics in n-doped InAs/GaAs self-assembled quantum dots by pump-probe midinfrared spectroscopy. A long T1 polaron decay time is measured at both low temperature and room temperature, with values around 70 and 37 ps, respectively. The decay time decreases for energies closer to the optical phonon energy. The relaxation is explained by the strong coupling for the electron-phonon interaction and by the finite lifetime of the optical phonons. We show that, even for a large detuning of 19 meV from the LO photon energy in GaAs, the carrier relaxation remains phonon assisted.

Journal Article↗
PubMed2001

Five novel RPGR mutations in families with X-linked retinitis pigmentosa.

X-linked forms of retinitis pigmentosa (XLRP) are among the most severe because of their early onset, often leading to significant visual impairment before the fourth decade. RP3, genetically localized at Xp21.1, accounts for 70% of XLRP in different populations. The RPGR (Retinitis Pigmentosa GTPase Regulator) gene that was isolated from the RP3 region is mutated in 20% of North American families with XLRP. From mutation analysis of 27 independent XLRP families, we have identified five novel RPGR mutations in 5 of the families (160delA, 789 A>T, IVS8+1 G>C, 1147insT and 1366 G>A). One of these mutations was detected in a family from Chile. Hum Mutat 17:151, 2001.

Carrier Proteins↗
PubMed2001

Acute mastoiditis--the antibiotic era: a multicenter study.

OBJECTIVES: To evaluate the clinical course and identify the causative organisms of acute mastoiditis in a community where most of the patients who develop acute otitis media are treated with antibiotics. METHODS: A multicenter retrospective review of a series of 223 consecutive cases of acute mastoiditis. SETTING: Nine secondary or tertiary academic or non-academic referral centers. RESULTS: Prior to the diagnosis of acute mastoiditis, 121 of the patients (54.3%) had been receiving oral antibiotic treatment for acute otitis media for periods ranging from 1 to 21 days (mean 5.3 days). Samples for bacterial culture were obtained from 152 patients. Cultures were negative in 60 patients. The organisms isolated in the 92 positive cultures were: Streptococcus pneumoniae (15 patients), Streptococcus pyogenes (14 patients), Staphylococcus aureus (13 patients), Staphylococcus coagulase negative (three patients), Pseudomonas aeruginosa (eight patients), Haemophilus influenzae (four patients), Proteus mirabilis (two patients), Escherichia coli (two patients), Klebsiella pneumoniae (one patient), Enterobacter (one patient), Acinetobacter (one patient), anaerobic gram-negative bacilli (one patient), and fungi (two patients). Ten patients had mixed flora. Sixteen patients presented with complications (cerebellar abscess, perisinus empyema, subdural abscess or empyema, extradural abscess, cavernous sinus thrombosis, lateral sinus thrombosis, bacterial meningitis, labyrinthitis, petrositis, or facial nerve palsy). CONCLUSIONS: Antibiotic treatment cannot be considered an absolute safeguard against the development of acute mastoiditis. Early myringotomy for acute otitis media seems to decrease the incidence of complications. The distribution of causative organisms in acute mastoiditis differs from that in acute otitis media. Intracranial complications in acute mastoiditis are not rare. Because of the diversity of causative organisms in acute mastoiditis and the growing resistance of bacteria to the various antibiotics, all means to obtain a sample for culture prior to antibiotic treatment, including general anesthesia.

Acute Disease↗
PubMed1999

Novel mutations in XLRS1 causing retinoschisis, including first evidence of putative leader sequence change.

Juvenile retinoschisis is an X-linked recessive disease caused by mutations in the XLRS1 gene. We screened 31 new unrelated patients and families for XLRS1 mutations in addition to previously reported mutations for 60 of our families (Retinoschisis Consortium, Hum Mol Genet 1998;7:1185-1192). Twenty-three different mutations including 12 novel ones were identified in 28 patients. Mutations identified in this study include 19 missense mutations, two nonsense mutations, one intragenic deletion, four microdeletions, one insertion, and one intronic sequence substitution that is likely to result in a splice site defect. Two novel mutations, c.38T-->C (L13P) and c.667T-->C (C223R), respectively, present the first genetic evidence for the functional significance of the putative leader peptide sequence and for the functional significance at the carboxyl terminal of the XLRS1 protein beyond the discoidin domain. Mutations in 25 of the families were localized to exons 4-6, emphasizing the critical functional significance of the discoidin domain of the XLRS1 protein.

Child↗
PubMed1997

[Toxic shock syndrome].

Toxic shock syndrome (TSS) is a rare, life-threatening, acute multisystem illness usually characterized by sudden onset of high fever, diffuse sunburn-like erythroderma and a variety of other signs and symptoms. It may progress rapidly to hypotension and shock with multiple organ failure. Its exact cause is unknown, but in almost all cases there has been an infection with exotoxin-producing strains of phage group I Staphylococcus aureus. Although initially described in association with the use of superabsorbent tampons in menstruation, TSS has complicated a variety of surgical procedures. Recently in head and neck surgery attention has focused on absorbent packing materials, such as those used in postoperative nasal care. TSS developed in a 12-year-old 28 hours after tonsillectomy, nasal septoplasty and inferior turbinectomy in which absorbent packing material was used. It is important to maintain a high index of suspicion for TSS in all postoperative patients with fever, hypotension and erythroderma.

Bandages↗
PubMed1996

Postradiotherapy hypothyroidism: radiation dose response and chemotherapeutic radiosensitization at less than 40 Gy.

To analyze our experience with iatrogenic hypothyroidism, we prospectively followed 84 patients, seen from 1984 to 1990, who had been diagnosed with either Hodgkin's disease (HD) or head and neck (H&N) carcinoma and subsequently treated with radiotherapy. Within these two diagnostic groups were subgroups whose treatment differed as to dose of therapeutic irradiation received or adjunctive use of chemotherapy. Approximately 50% of all patients and of each subgroup developed either clinical or subclinical hypothyroidism during follow-up. However, among the HD patients who received irradiation plus chemotherapy, a dose-response relationship below a threshold limit of dose received, probably 40 Gy, was observed.

Adolescent↗
PubMed1994

Foveal thickening in retinitis pigmentosa patients with cystoid macular edema.

PURPOSE: Clinical evaluation of cystoid macular edema (CME), known to occur in patients with retinitis pigmentosa (RP), is based on the presence of vascular leakage on fluorescein angiography. Due to an inability to quantitatively assess retinal thickening, the degree of thickening from fluid accumulation and its relation to fluorescein dye leakage into the extravascular retinal space has not been established. The relationship between fluorescein dye leakage and foveal thickening and the effect of methazolamide treatment was studied. METHODS: The retinal thickness analyzer was used to measure the degree of thickening in six patients with RP and CME. A laser beam was projected at an oblique angle to the retina, and images of the intersection of the laser slit with the anterior and posterior retinal surfaces were recorded. The digitized images were analyzed using a dedicated software program to provide quantitative measurements of retinal thickness. Routine fluorescein angiography was performed. RESULTS: The amount of fluorescein dye leakage was not indicative of the degree of retinal thickening due to fluid accumulation. Foveal thickening and fluorescein dye leakage were reduced in five of six eyes after methazolamide treatment. Eyes with moderate thickening reversed to normal, whereas eyes with severe thickening showed only a minimal reduction in thickness. CONCLUSION: Retinal thickness measurement is a useful method of evaluating both the extent of and changes in retinal thickness after carbonic anhydrase treatment.

Adult↗
PubMed1991

Rhodopsin mutations in autosomal dominant retinitis pigmentosa.

DNA samples from 161 unrelated patients with autosomal dominant retinitis pigmentosa were screened for point mutations in the rhodopsin gene by using the polymerase chain reaction and denaturing gradient gel electrophoresis. Thirty-nine patients were found to carry 1 of 13 different point mutations at 12 amino acid positions. The presence or absence of the mutations correlated with the presence or absence of retinitis pigmentosa in 174 out of 179 individuals tested in 17 families. The mutations were absent from 118 control subjects with normal vision.

Base Sequence↗