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Biomedical subjects

M Goldschmidt

Publications and source records attributed to M Goldschmidt.

At least 19 recordsLinked to original sources
PubMed2004

Can fixation instability improve text perception during eccentric fixation in patients with central scotomas?

BACKGROUND: Oculomotor behaviour was investigated in 14 patients with central scotomas from age related macular degeneration (AMD) or Stargardt's disease. A scanning laser ophthalmoscope (SLO) was used to project letters and words onto the retina and to assess fixation behaviour. Five patients reported while deciphering letters that they needed to "move their eye" to prevent the image from vanishing. The observation of the SLO fundus images revealed that the gradual disappearance of the stimulus did not result from a transient projection of the word in the lesion. This prompted the authors to investigate, in an experimental setting, whether purposeful changes in fixation position could improve the perception of an eccentrically fixated text stimulus. METHODS: Twenty normal subjects were asked to alternate fixation, every three to four seconds, between two vertically aligned dots, spaced 10 degrees apart, and to report any changes in the perception of a laterally located letter, 1.5 degrees in height, 7 degrees apart and equidistant between the two fixation spots. RESULTS: Nineteen subjects reported a transient refreshment of the letter image immediately after the realisation of a saccade. Improved perception lasted approximately a second. With persistent fixation, they noted a rapid fading effect that reduced letter recognition. CONCLUSION: These observations suggest that ocular instability during eccentric viewing can have a functional advantage, probably related to counteracting Troxler's phenomenon. In addition to alternating between PRLs, it appears that saccades related to fixation instability might be valuable and improve text perception in individuals with a central scotoma and eccentric fixation. This possibility should be taken into consideration when conducting visual rehabilitation procedures.

Adult↗
PubMed2001

Cutting edge: systemic inhibition of angiogenesis underlies resistance to tumors during acute toxoplasmosis.

The ability of various infections to suppress neoplastic growth has been well documented. This phenomenon has been traditionally attributed to infection-induced concomitant, cell-mediated antitumor immunity. We found that infection with Toxoplasma gondii effectively blocked neoplastic growth of a nonimmunogenic B16.F10 melanoma. Moreover, this effect was independent of cytotoxic T or NK cells, production of NO by macrophages, or the function of the cytokines IL-12 and TNF-alpha. These findings suggested that antitumor cytotoxicity was not the primary mechanism of resistance. However, infection was accompanied by strong, systemic suppression of angiogenesis, both in a model system and inside the nascent tumor. This suppression resulted in severe hypoxia and avascular necrosis that are incompatible with progressive neoplastic growth. Our results identify the suppression of tumor neovascularization as a novel mechanism critical for infection-induced resistance to tumors.

Acute Disease↗
PubMed2000

[Follow-up of patients suffering from age-related macular degeneration, supplied with visual aids].

BACKGROUND: Age-related macular degeneration (AMD) is at present the major cause of legal blindness in industrialized countries. The results of various treatments are often not satisfactory and follow-up by Low-Vision services is then the only solution for this population. Few studies have been published on this subject. The purpose of this study is to present the use of magnifying systems and the degree of satisfaction obtained for this series of patients 6 months after prescription. PATIENTS AND METHODS: Forty-four patients were examined, 42 of whom were eligible for the study. Lenses, magnifying glasses, visual systems for intermediate distance, and electronic systems were proposed. A low-vision training was given to every patient. RESULTS: The highest degree of use and satisfaction was achieved with the electronic systems. In some cases, however, the other systems were well accepted by the patients. CONCLUSION: The follow-up of patients with age-related macular degeneration is of great social importance. The independence of elderly people can be safeguarded thanks to the help of Low-Vision services with a good equipment and a well-trained team. Sometimes, unsophisticated systems such as magnifying glasses can be proposed, but the best results are mostly obtained through electronic systems (TV).

Aged↗
PubMed1998

Environmental causes for sinonasal cancers in pet dogs, and their usefulness as sentinels of indoor cancer risk.

A case-control study was conducted to investigate the environmental causes of sinonasal cancers among pet dogs. Sinonasal cancer (SNC) cases and digestive cancer controls from the years 1989 through 1993 were obtained from a veterinary histopathology database. Owners were mailed a self-administered survey requesting information on canine factors, owner demographics, household exposures (including environmental tobacco smoke), and local pollution. A total of 129 case owners and 176 control owners returned completed surveys: a response rate of approximately 72%. Only household exposures were associated with increased SNC risk. Use of indoor coal or kerosene heaters represented the strongest risk factors, with significant adjusted odds ratios of 4.2 and 2.2 respectively. Environmental tobacco smoke exposure was not a risk factor and was suggestive of a nonsignificant, mildly protective effect at the lower exposure levels. Increasing nasal length was a significant risk factor, and there was effect modification between nasal length and coal or kerosene combustion. No self-reported measures of local pollution, such as urban status or residence within 1 mile of a factory, were associated with SNC risk. These results suggest that canine SNC has a strong environmental component and highlight the importance of indoor exposures, especially from fossil fuel combustion products. These results also suggest that pet dogs represent excellent sentinels for indoor cancer risk and that canine SNC cases can be used as early markers of household exposure to carcinogenic combustion products.

Air Pollution, Indoor↗
PubMed1998

In vivo inflammatory response to a prototypic B cell superantigen: elicitation of an Arthus reaction by staphylococcal protein A.

Staphylococcal protein A (SpA) is representative of a new class of Ags, the B cell superantigens (SAgs). These SAgs, unlike conventional Ags, bind to the Fab regions of Ig molecules outside their complementarity-determining regions. In addition, B cell SAgs can react with a substantial amount of a host's serum Igs by virtue of their ability to interact with many members of an entire variable heavy chain (VH) or variable light chain gene family. For example, SpA reacts with the Fabs of most human Igs using heavy chains from the VH3 gene family (VH3+). Members of this gene family are expressed on 30 to 60% of human peripheral B cells. We sought to determine whether the interaction of a B cell SAg with its reactive Igs can elicit immune complex-mediated tissue injury. Using the Arthus reaction in rabbits as an in vivo model of immune complex-mediated tissue inflammation, we demonstrated that untreated rabbits, which were administered SpA intradermally (i.d.), do not develop a cutaneous inflammatory response. However, when rabbits were pretreated i.v. with human IgG (hIgG), i.d. injections of SpA induced an inflammatory response with the classical histologic features of an Arthus reaction. To determine whether this Arthus-like response occurred via a B cell superantigenic mechanism, the rabbits were pretreated with VH3-depleted hIgG and then were administered SpA i.d. We found that the induction of a prominent inflammatory response by SpA was dependent upon the presence of VH3+ molecules in the hIgG pretreatment. These results provide compelling evidence that an interaction of the B cell SAg, SpA, with its reactive (VH3+) IgGs leads to an immune complex-mediated inflammatory response in vivo.

Animals↗
PubMed1998

[Management of children with low vision].

Presentation of the Lausanne school for blind and visually impaired children. 38 children were admitted in the school in 1996-1997. 16 have a visual acuity of less than 3/60. Ocular malformations of various origins are the main reason of the handicap, followed by visual lesions of central origin. Comparing the study with those of 1992 and 1993, it seems that the number of retrolental fibroplasia and cataracts (operated or not) is decreasing. The authors present the educational care of these children. At present, the goal is to maintain the children in their own family. Most of them are day pupils and the transportation organisation is therefore very important. In special cases, it is possible to leave the children in a non-specialized school, provided the children receive a good educational support by one of our specialized low-vision teachers.

Adolescent↗
PubMed1996

Mice lacking the TNF receptor p55 fail to resolve lesions caused by infection with Leishmania major, but control parasite replication.

TNF is involved in host resistance to several pathogens. Recently it was found that mice lacking the p55 receptor for TNF (TNFRp55 -/-) do not control growth of the intracellular bacteria, Listeria monocytogenes and Mycobacterium tuberculosis. Here we report that the course of infection in TNFRp55 -/- mice with another intracellular pathogen, the protozoan parasite Leishmania major, is also quite different from normal mice. TNFRp55 -/- mice developed larger lesions than control mice and failed to resolve these lesions. However, they were able to eliminate parasites within the lesions. Histologic analysis indicated that at late stages lesions from TNFRp55 -/- mice appeared similar to lesions associated with cutaneous graft-vs-host disease. Both TNFRp55 -/- and control mice developed a normal Th1-type response during infection. We also found that IFN-gamma-activated macrophages from TNFRp55 -/- mice produced nitric oxide and killed L. major in vitro, which correlated with the ability of TNFRp55 -/- mice to eliminate the parasites in vivo. The production of nitric oxide by macrophages from TNFRp55 -/- mice required the presence of the parasites, however, since in their absence TNF could only synergize with IFN-gamma for nitric oxide production when added to normal, but not TNFRp55 -/-, macrophages. These results indicate that neither macrophage microbicidal activity nor nitric oxide production is absolutely dependent on the p55 receptor for TNF. Furthermore, they uncover a previously undefined role for TNFRp55 in resolution of parasite-induced inflammatory lesions.

Animals↗
PubMed1996

Nicorandil: a potassium channel opening drug for treatment of ischemic heart disease.

Nicorandil is the first oral potassium channel activating drug to be used for the treatment of symptomatic coronary artery disease. It appears to relax vascular smooth muscle through membrane hyperpolarization via increased transmembrane potassium conductance and, like nitrates, through an increase in intracellular cyclic GMP. In addition, nicorandil, in a nitrate-like manner, dilates normal and stenotic coronary arteries and reduces both ventricular preload and afterload. In contrast to nitrates, however, nicorandil does not appear to cause tolerance with long-term administration. In placebo and comparison clinical trials, nicorandil has demonstrated some efficacy and safety in patients with both stable and vasospastic angina pectoris, and it was found to be a myocardial protective agent in animal studies. The antianginal activity of nicorandil, however, is relatively short lived after dosing, which will necessitate the development of extended-release formulations of the drug.

Clinical Trials as Topic↗
PubMed1994

Microbial contamination in four commercially available denture adhesives.

Four brands of commercially available powder denture adhesives were tested for microbial contamination. Sterile Petri plates that contained either brain-heart infusion (BHI) or Sabouraud's (SAB) agar were inoculated with 0.5 gm samples of each adhesive. The BHI plates were incubated aerobically and anaerobically at 35 degrees C and the SAB plates aerobically at 30 degrees C for 2 weeks. The sterility of these procedures was confirmed by incubating uninoculated control plates. All bottles of powder denture adhesive tested contained microorganisms. Both bacterial and fungal growth were noted. The containers of adhesive were then subjected to 10 minutes of microwave energy (650 W) to sterilize the adhesive material. After retesting, any bottles still contaminated were subjected to additional 10 minutes of microwave exposure and then retested. Seven of 24 bottles still showed evidence of microbial contamination after exposure to microwave energy. Of the seven bottles, five were of one brand. A Fisher's exact test showed significant differences in the percentage of contaminated samples between that and the other brands (p < 0.05). Microwave energy reduced microbial contamination in all samples but failed to completely sterilize seven of 24 samples.

Adhesives↗
PubMed1989

Prognostic factors and survival after radiotherapy for intranasal neoplasms in dogs: 70 cases (1974-1985).

Survival time and 31 prognostic factors were analyzed for 70 dogs undergoing radiotherapy for intranasal tumors at the Veterinary Hospital of the University of Pennsylvania between 1974 and 1985. At the time of analysis (January 1987), 14.3% (10 of 70) of the dogs were alive. Of the remaining dogs, 34 died because of tumor recurrence, 14 died because of intercurrent disease, and 12 were lost to follow-up evaluation. Pretreatment prognostic factors that were significantly correlated with disease-free interval or long-term survival could not be identified. Notably, presence of a facial mass was not prognostically significant, suggesting that extensive disease should not preclude treatment. Median survival time of dogs with all tumor types was 16.5 months, with a 1-, 2-, and 3-year survival of 54%, 43%, and 35%, respectively. Median survival time of dogs with carcinoma was 13.5 months, with 1-year survival of 51%, 2-year survival of 37%, and 3-year survival of 31%. Orthovoltage radiation was efficacious in the treatment of canine intranasal tumors.

Animals↗
PubMed1989

Simultaneous use of microfibrillar collagen hemostat and blood saving devices in a canine kidney perfusion model.

Intraoperative autotransfusion and topical microfibrillar collagen hemostats have been increasingly used, often simultaneously, in various surgical procedures to minimize intraoperative blood loss and thus reduce the inherent risks of homologous blood transfusion. As moderate amounts of small particles have been shown to pass through filtering devices during intraoperative autotransfusion, concern has been raised over the amount of heterologous collagen fibrils transfused and their effect on the host. We found that 2% of microfibrillar collagen hemostat particles pass through the 20-microns millipore filter contained in the tested autotransfusion device (William Harvey H-4700 cardiotomy reservoir). Using a canine kidney perfusion model, we found multifocal perivascular inflammatory reactions within the renal parenchyma five days after transfusion of filtered autologous blood containing minute amounts of microfibrillar collagen hemostat. The findings demonstrate a strong inflammatory foreign body response to heterologous collagen particles trapped in the microcirculation of the perfused kidneys. It is concluded that despite using filters with a pore size of 20 microns, using intraoperative autotransfusion and microfibrillar collagen hemostats simultaneously creates a potential risk because adverse reactions can be elicited especially within the microvasculature of tissues containing end-arterial circulation.

Animals↗
PubMed1986

Long-term renal responses to high dietary protein in dogs with 75% nephrectomy.

It has been proposed that ingestion of large amounts of dietary protein leads to sustained renal hyperperfusion and progressive glomerulosclerosis in rats. This hypothesis was tested in dogs, with 75% reduction in renal mass, maintained for 4 years on either 56, 27, or 19% dietary protein. Twelve of 21 dogs survived 4 years, and death due to renal failure was not correlated to diet. Dogs fed 56 and 27% protein had increased GFR and CPAH before and after reduction of renal mass compared to the 19% group. A pattern of deterioration of renal function, including proteinuria, was not found in any diet group. Nine of 11 dogs, fed 56, 27, or 19% protein had minimal glomerular lesions, including mesangial proliferation, GBM irregularities, adhesions, and sclerosis. Two other dogs, fed 56% protein, had more severe glomerular lesions. No significant ultrastructural differences were found in glomeruli among the three diet groups. These results do not support the hypothesis that high protein feeding had a significant adverse effect on either renal function of morphology in dogs with 75% nephrectomy.

Animals↗