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H Kahn

Publications and source records attributed to H Kahn.

At least 19 recordsLinked to original sources
PubMed1999

MR imaging of intrarenal macrophage infiltration in an experimental model of nephrotic syndrome.

The objective of this study was to use MR imaging to detect macrophage infiltration of the kidney after injection of ultrasmall superparamagnetic iron oxide (USPIO) particles in a rat model of experimental nephropathy. Ninety micromol of USPIO were injected intravenously in 10 rats with nephropathy secondary to intravenous injection of 5 mg of puromycin aminonucleoside (PAN), and in 10 control rats. The signal intensity was measured in each kidney compartment before and 24 h after injection of the contrast agent. FLASH sequences were performed on a spectrometer operating at 4.7 T. MR findings were compared with histological data. Twenty-four hours after injection of USPIO, a significant decrease (P < 0.0001) was observed in signal intensity in each kidney compartment in the PAN group. There was no variation in the control group. In the diseased kidneys, histological data revealed the presence of macrophages with iron oxide particles within their cytoplasm and lysosomes. Using USPIO, MR imaging can evidence infiltration of the rat kidney by macrophages.

Animals↗
PubMed1999

Laboratory evaluations of feed-grade and agricultural-grade phosphates.

Nine samples of pure, feed-grade (FP) and agricultural-grade (AP) phosphates were evaluated at seven laboratories (six in Brazil and one in the U.S.) for physical and chemical characteristics. Phosphates were one "standard" pure dicalcium phosphate; four FP, two dicalcium phosphates (FP-1 and FP-2) made in Brazil, one di-monocalcium phosphate (FP-3), and one defluorinated phosphate (FP-4) made in the U.S.; and four AP made in Brazil [single superphosphate (AP-1), triple superphosphate (AP-2) and monoammonium (AP-3), and thermomagnesium (AP-4) phosphates]. Average analytical values for FP and AP, respectively, were 3.3 and 6.3% moisture, 1.0 and 2.5% insoluble residue, 16.2 and 28.4% loss on ignition, 6.8 and 4.7 (pH), 1,028 and 1,023 g/L apparent density, 9.6 and 55.0% P solubility in water, 83.6 and 88.4% P solubility in 2% citric acid, and 85.2 and 97.0% P solubility in neutral ammonium citrate. Based on particle size, six products were classified as "fine," and three were classified as "irregular." Atomic absorption and plasma spectrometry determinations were performed for 31 essential and potentially harmful or radioactive minerals. The Na level was high in FP-4 (6.03%). Mineral concentrations were safe for all FP as compared with NRC standards. Levels in AP were toxic, exceeding the tolerance limits for F, Fe, Mg, and Ba, and were particularly high as compared with FP for S, Ti, and radioactive Th. The AP-1 was high in F, Ba, S, and Th; AP-2 and AP-3 were high in F and S; and AP-4 was high in F, Ba, Fe, Mg, Ti, and Th. X-ray diffraction assays detected impurities for all commercial samples and identified as major components CaHPO4*2H2O (standard phosphate), CaCO3 and CaHPO4 (FP-1, FP-2, and FP-3), Ca(H2PO4)2*H2O (FP-3), Na2Ca3Al2(PO4)2(SiO4)2 and Ca3(PO4)2 (FP-4), CaSO4*nH2O and (NH4)Fe3P6O20*(PO4)2 (AP-1), Ca(H2PO4)2*H2O and KFe3P6O20*10H2O (AP-2), (NH4)H2PO4 and CaSO4*nH2O (AP-3), and no definite molecular structure for AP-4, an amorphous product. The biological consequences of feeding animals a mineral source with no definite molecular structure, an amorphous product, is not known. A biological evaluation of all phosphates included in this article is being published as a separate report (Fernandes et al., 1999).

Agriculture↗
PubMed1999

Pseudogaucher cells in cutaneous Mycobacterium avium intracellulare infection: report of a case.

We report on a patient infected with human immunodeficiency virus, and with cutaneous Mycobacterium avium intracellulare, in whom many cells with abundant reticulated cytoplasm resembling the characteristic cells of Gauchers disease ("pseudogaucher cells") were noted within the dermal infiltrate on biopsy. Although pseudogaucher cells have been reported in association with M. avium intracellulare infection in extracutaneous sites, this is, to our knowledge, the first report of cutaneous pseudogaucher cells in the skin.

Acquired Immunodeficiency Syndrome↗
PubMed1998

Subcortical connections of normotopic and heterotopic neurons in sensory and motor cortices of the tish mutant rat.

Orthograde and retrograde tracers were used to examine subcortical connections of neurons in the neurological mutant tish rat. This animal exhibits bilateral heterotopia similar to those observed in epileptic humans with subcortical band heterotopia. Terminal varicosities were labeled in the striatum, thalamus, brainstem, and spinal cord following injections of the anterograde tracer biotinylated dextran amine (BDA) into the heterotopic cortex. The general topography of corticothalamic projections was evaluated by injecting the retrograde tracer Fluoro-Gold (FG) into ventral thalamic nuclei. Retrograde labeling of small-to-medium sized neurons was observed in layer VI of topographically restricted portions of the normotopic cortex. Similar appearing cells were labeled in the neighboring portions of the underlying heterotopia; however, these neurons did not display characteristic lamination or radial orientation. Thalamocortical terminals labeled by injecting BDA into the ventroposterolateral nucleus (VPL) were observed primarily in layer IV of the medial aspect of the normotopic somatosensory cortex. In contrast, a radial column of terminals was present in the underlying heterotopia. Typical barrel labeling was found in the lateral aspect of the normotopic somatosensory cortex after injecting the ventroposteromedial nucleus (VPM), whereas more diffuse patches of labeling were observed in the underlying heterotopia. Heterotopic neurons in the tish cortex, thus, exhibit characteristic features of subcortical connectivity. Both normotopic and heterotopic neurons in the tish brain project to appropriate subcortical sites and establish bidirectional topographic connections with the thalamus. These results suggest that primary sensory-motor information is represented in a parallel manner in the normotopic and heterotopic cortices of the tish rat.

Afferent Pathways↗
PubMed1997

Preoperative staging of irradiated rectal cancers using digital rectal examination, computed tomography, endorectal ultrasound, and magnetic resonance imaging does not accurately predict T0,N0 pathology.

PURPOSE: The postradiation preoperative staging results of 25 patients with rectal cancer who were found to have Stage T0,N0 lesions after surgery were examined. Our aim was to assess the ability of preoperative staging following radiation therapy to predict the absence of disease. METHODS: From 1983 to 1994, 25 patients treated with preoperative radiation therapy for biopsy-proven rectal cancer were found to have no pathologic evidence of disease in the resected specimen (T0,N0). The preoperative postradiation disease staging results of these patients were compared with the postoperative pathologic findings. Each patient received 4,500 to 5,580 cGy during a five-week to six-week period, and four patients had preoperative chemotherapy. Surgical resection was performed six to eight weeks after completion of radiation therapy. All 25 patients were staged by digital rectal examination before surgery. In addition, 13 patients were assessed using computed tomography, 6 by endorectal ultrasound, and 1 by magnetic resonance imaging. RESULTS: Most irradiated lesions were overstaged by radiologic assessment and physical examination. No technique could reliably distinguish between postradiation fibrosis and residual cancer. The negative predictive value for digital rectal examination was 24 percent. Computed tomography accurately staged 23 percent of lesions, and endorectal ultrasound predicted 17 percent of lesions correctly. The single patient evaluated by magnetic resonance imaging was overstaged and thought to have a T2 lesion. CONCLUSIONS: Our ability to assess local eradication of rectal cancer following radiation therapy remains poor. Conventional imaging and clinical examination techniques are unable to safely predict which patients do not require surgical excision following curative radiation therapy for rectal cancer.

Adenocarcinoma↗
PubMed1996

Factors associated with local breast cancer recurrence after lumpectomy alone.

BACKGROUND: The purpose was to determine the rate of local breast relapse in patients with breast cancer uniformly treated with partial mastectomy but without postoperative radiotherapy and without systemic adjuvant therapy. We also systematically examined the factors associated with local recurrence to determine whether a low-risk subgroup existed. METHODS: A retrospective review of a prospectively followed (median, 8 years) cohort of 293 patients was performed. The end-point was ipsilateral local breast cancer recurrence. The patient's age, tumor size, nodal status, estrogen and progesterone receptor status, histology, and tumor and nuclear grade were studied, as were the presence and amount of carcinoma in situ and the presence of tumor emboli using univariate Kaplan-Meier and Cox step-wise multivariate analyses. RESULTS: The overall local relapse rate was 26% (77 recurrences). Univariate factors significantly associated with decreased local relapse included older age, negative nodes, small tumor size, positive estrogen receptor status, and absence of tumor emboli. Significant multivariate variables were age, nodal status, estrogen receptor status, absence of comedo carcinoma in situ, and tumor emboli. A low-risk subgroup of 66 patients was defined with a 6% 10-year local recurrence rate. CONCLUSION: Important patient and tumor variables associated with local breast cancer relapse after breast-conserving surgery can define a low-risk subgroup.

Adult↗
PubMed1996

Clinical behavior of untreated axillary nodes after local treatment for primary breast cancer.

BACKGROUND: The purpose of this study was to examine the rate of axillary failure in patients with primary breast cancer treated without axillary dissection or radiation and to determine what factors may be associated with axillary failure. METHODS: We studied 112 patients with invasive breast cancer treated for primary disease with breast-conserving surgery without axillary dissection or radiation to the breast or axilla, accrued between 1977 and 1986. Data for these patients were prospectively gathered for a research database and reviewed retrospectively to determine axillary failure. The effects of age, tumor size, estrogen receptor (ER) status, progesterone receptor (PgR) status, histologic grade, nuclear grade, and tumor emboli on time to axillary failure were examined. RESULTS: The median follow-up was 9.6 years. There were 26 axillary recurrences, resulting in a 10-year actuarial nodal control rate of 72%. Patients with nodal failure proceeded to axillary dissection with minimal morbidity. In both univariate and multivariate analyses, only tumor size was significantly associated with axillary failure (p = 0.04 and p = 0.06, respectively). CONCLUSIONS: This study demonstrates a significant effect of tumor size on axillary failure and a reasonable rate of local control in small tumors. Further research should examine the utility of axillary dissection in women with small breast cancers.

Actuarial Analysis↗
PubMed1996

IUD users in Norway are at low risk for genital C. trachomatis infection.

From May 1993 to April 1995, 30 general practitioners located at 13 general practice settings in the city of Trondheim, central Norway, recruited 957 eligible participants in a prospective use-effectiveness study on performance of two copper IUDs. In this report we focus on screening for C. trachomatis at insertion and its possible effect on cause-related terminations during the first 90 days after insertion. All women were screened at IUD insertion for C. trachomatis. All specimens were analyzed applying a nucleic acid test (rRNA, GenProbe). Five out of 957 women (0.5%) were positive for C. trachomatis. All were treated within two weeks of diagnosis. No cases of pelvic inflammatory disease were diagnosed during the first three months of the study. Screening of C. trachomatis at IUD insertion is not recommended in Norwegian women because of the extremely low prevalence of C. trachomatis in those who choose IUD as their primary contraceptive method. Recommendations for universally screening women for sexually transmitted diseases at IUD insertion should be based upon review of local/national prevalence data.

Adolescent↗
PubMed1995

The Henrietta Banting Breast Centre database: a model for clinical research utilizing a hospital-based inception cohort.

The cohort study design has been used successfully in clinical cancer research. Cohorts, however, are valuable only if they produce results which are valid and generalizable. Some hospital-based inception cohorts satisfy both these requirements and may thus be useful research tools. The development of one such hospital-based cohort, the Henrietta Banting Breast Centre database, is described. This cohort is composed of 1097 women diagnosed with primary breast cancer at Women's College Hospital, Toronto, from January 1977 through December 1986. Details of diagnostic procedures, pathology, treatment, dates and sites of recurrence, and date of death are available on 96% of women. By comparison with published series and with the Ontario Cancer Registry, we have demonstrated validity and generalizability. A major advantage is the ready availability of paraffin tissue blocks on virtually all cases, facilitating analyses of the prognostic importance of specific biologic variables and immunocytochemical hormone assays. Other completed studies and future uses of the cohort are described.

Breast Neoplasms↗
PubMed1995

Chemical and physical evaluations of commercial dicalcium phosphates as sources of phosphorus in animal nutrition.

Seven samples of commercial dicalcium phosphate, expected to contain variable amounts of monocalcium phosphate, from five established producers in Brazil and two in the United States, were evaluated and compared with a purified grade calcium phosphate dibasic dihydrate used as a reference standard. All samples were submitted to a wide range of tests at seven laboratories. Each determination was performed at least at two different laboratories, except for moisture, insoluble residue, loss on ignition, and x-ray diffraction assays, obtained from one single laboratory. All phosphate samples studied were in compliance with the manufacturer's levels of guarantee, except for three samples that were slightly out of specification (Ca, P, and F). Particle size patterns were variable, allowing for a classification of two products as "coarse", three as "fine", and three as "irregular". Phosphorus solubility in 2% citric acid ranged from 85.9 to 97.6%, pH from 3.2 to 6.1, and apparent density from 572 to 967 g/L. Atomic absorption or plasma emission spectrometry concentrations (average parts per million) for Al (3,200), As (10), B (14), Ba (165), Bi (< .1), Cd (6), Cr (57), Co (11), Cu (28), Fe (7,515), Hg (< .2), Mg (11,300), Mn (367), Mo (6), Ni (25), Pb (17), Se (< .5), Sb (1.3), Th (19), U (51), V (134), W (< 5), and Zn (152) were safe for all phosphates as compared to NRC standards. X-ray diffraction detected CaCO3 and impurities for all commercial samples, dolomite for three phosphates. Monocalcium phosphate was found in four samples. Aluminum salts present were identified as the low solubility, low toxicity silicates, and phosphates.

Animal Feed↗
PubMed1993

Multiple hamartoma syndrome with osteosarcoma.

Multiple hamartoma syndrome, also known as Cowden's disease, is a rare genodermatosis with characteristic mucocutaneous lesions associated with multiple internal abnormalities. We describe a patient having classic dermatologic manifestations of Cowden's disease and multiple neoplasia including follicular adenocarcinoma of the thyroid gland with lung metastasis, intraductal breast carcinoma within a fibroadenoma, and an osteosarcoma. To our knowledge, this is the first reported case of an osteosarcoma in Cowden's disease.

Adult↗
PubMed1992

A comparison of all-subset Cox and accelerated failure time models with Cox step-wise regression for node-positive breast cancer.

Clinical studies usually employ Cox step-wise regression for multivariate investigations of prognostic factors. However, commercial packages now allow the consideration of accelerated failure time models (exponential, Weibull, log logistic, and log normal), if the underlying Cox assumption of proportional hazards is inappropriate. All-subset regressions are feasible for all these models. We studied a group of 378 node positive primary breast cancer patients accrued at the Henrietta Banting Breast Centre of Women's College Hospital, University of Toronto, between January 1, 1977, and December 31, 1986. 85% of these patients had complete prognostic factor data for multivariate analysis, and 96% of the patients were followed to 1990. There was evidence of marked departures from the proportional hazards assumption with two prognostic factors, number of positive nodes and adjuvant systemic therapy. The data strongly supported the log normal model. The all-subset regressions indicated that three models were similarly good. The variables 1) number of positive nodes, 2) tumour size, and 3) adjuvant systemic therapy were included in all three models along with one of three biochemical receptor variables 1) ER, 2) combined receptor (ER- PgR-; ER+PgR-; ER- PgR+; ER+PgR+; or 3) PgR. Better multivariate modeling was achieved by using quantitative prognostic factors, a check for appropriate underlying model-type, and all-subset variable selection. All-subset regressions should be considered for routine use with the many new prognostic factors currently under evaluation; it is very possible that there may not be a single model that is substantially better than others with the same number of variables.

Adult↗
PubMed1992

Peripancreatic lymph node gastrinoma in a patient with Zollinger-Ellison syndrome.

The case of a patient who had Zollinger-Ellison syndrome caused by a primary peripancreatic lymph node gastrinoma is presented. Accompanying diffuse pancreatic islet cell hyperplasia, a well-documented occurrence in hypergastrinemia, was present. A perforated esophageal ulcer in a Barrett's esophagus led to right-sided necrotizing pleuritis, septicemia, and death. The diffuse parathyroid hyperplasia also noted in the patient is thought to be secondary to chronic hypertensive renal failure rather than MEN-I syndrome.

Aged↗
PubMed1991

Human immunodeficiency virus-associated Hodgkin's disease. Clinicopathologic studies of 24 cases and preponderance of mixed cellularity type characterized by the occurrence of fibrohistiocytoid stromal cells.

Hodgkin's disease (HD) was diagnosed in 24 patients who were either seropositive for human immunodeficiency virus (HIV) (21) or members of a high-risk group (three), but had not developed acquired immune deficiency syndrome (AIDS). Clinical presentation of the disease was characterized by constitutional symptoms in all, especially fever (23/24) and disseminated disease (22/24) at diagnosis. Mediastinal adenopathy was rare. Bone marrow involvement was particularly frequent (12/24), and a positive bone marrow biopsy preceded lymph node biopsy in 5 of the 12. Histopathologic features of these tumors included an increased number of nonlymphoid stromal cells, i.e., histiocytic and/or fibroblastoid. In some tumors these fibrohistiocytoid stromal cells were arranged in bundles, but distinct nodule with birefringent collagen band formation was not observed. Twenty-two patients were treated, most with combination chemotherapy; one was untreated; one, unknown. Sixteen, including the one untreated, died with disease at 3 to 25 months; one died of an unrelated cause; four were alive at 3 to 24 months; three were lost to follow-up. Frequent bone marrow involvement at presentation suggests the usefulness of the bone marrow biopsy for diagnosis in subjects at risk, especially when they present with spiking fever of unknown origin. Contrary to most previous series, virtually all of our cases were of mixed cellularity type, characterized by increased fibrohistiocytoid stromal cells in place of depleting lymphocytes. The classic nodular sclerosing feature with birefringent collagen band formation was not observed. In conclusion, HIV-associated HD was characterized by advanced stage with fever at presentation, preponderance of mixed cellularity histologic type with increased fibrohistiocytoid stromal cells, and poor outcome. Hodgkin's disease in AIDS patients presents an intriguing biological model to study the role of stromal histiocytes in immunodeficient patients.

Adult↗
PubMed1991

Acute biologic response to excimer versus thermal laser angioplasty in experimental atherosclerosis.

Vascular injury and platelet accumulation after balloon angioplasty are two potentially important triggers of the process of restenosis that may be minimized by the use of laser energy to ablate atherosclerotic plaque. The type of laser most suitable to achieve these goals remains unknown. Accordingly, angiographic and histologic studies and quantitative platelet deposition analysis were performed on 27 atherosclerotic rabbit iliac arteries randomized to treatment with excimer laser or thermal laser angioplasty. Excimer laser angioplasty was achieved with 35 to 40 mJ/mm2 of 308 nm xenon chloride irradiation delivered through a 4.5F catheter made of 13 concentrically arranged 200 microns fiber optics, at a repetition rate of 25 to 30 Hz and a pulse duration of 135 ns; thermal laser angioplasty was achieved with a 1.7 mm metal probe heated with 10 W of continuous wave argon laser energy. The baseline and post-laser luminal diameters of excimer laser-treated vessels (0.92 +/- 0.28 and 1.56 +/- 0.48 mm, respectively) were similar to those observed in thermal laser-treated vessels (1.05 +/- 0.44 and 1.61 +/- 0.41 mm, respectively). Perforation occurred in 4 (29%) of 14 thermal laser-treated arteries and in 0 of 13 excimer laser-treated arteries (p = 0.04); spasm was observed in only 1 thermal laser-treated vessel. On the basis of a quantitative histologic grading scheme (damage scores of 0 to 4), greater degrees of injury were measured in thermal versus excimer laser-treated vessels (2.4 +/- 1.0 versus 1.3 +/- 0.4, p = 0.009).(ABSTRACT TRUNCATED AT 250 WORDS)

Angioplasty, Laser↗