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V A Fadok

Publications and source records attributed to V A Fadok.

53 records · Page 3Linked to original sources
PubMed1992

The mechanism of internalization of platelet-activating factor in activated human neutrophils. Enhanced transbilayer movement across the plasma membrane.

Recent studies suggest that cellular internalization of platelet-activating factor (PAF), a potent ether phospholipid mediator of inflammation, is modulated by, as yet undefined cellular mechanisms. Using an albumin extraction method, the internalization of PAF and several PAF analogues was studied in the resting and stimulated human neutrophil. Our data demonstrate that internalization of these analogues is largely dependent on the state of cellular activation and that the process is not specific for certain unique structural features of the PAF molecule including the 1-position ether linkage, 2-position acetyl substitution, or choline polar head group. Furthermore, the internalization process was shown not to be dependent on the PAF receptor, metabolism of the molecule, or the process of endocytosis. Data are presented to suggest that the route of internalization of PAF is enhanced transbilayer movement (flipping) across the plasma membrane occurring as a result of changes in membrane physical properties accompanying cellular activation. It is proposed that in addition to enhanced internalization of PAF, modulation of PAF biosynthesis and net release from the stimulated neutrophil may be consequences of enhanced transbilayer movement of PAF across the activated plasma membrane.

Biological Transport↗
PubMed1992

Apoptosis and programmed cell death in immunity.

Death of some cells in the mammalian body is clearly programmed. In the immune system there are many examples of programmed cell death, during development of lymphocytes as well as at later stages, after interaction with antigen. Many of these examples display the morphology of apoptosis: They undergo shrinkage and zeiosis, the nucleus collapses, and chromatin is cleaved into nucleosomal fragments. The cell is rapidly recognized by phagocytes and disposed of without releasing its contents. In some but not all cases of apoptosis, new macromolecular synthesis is required. Cytotoxic T cells induce changes in their targets that are morphologically apoptotic. The mechanism of apoptosis is currently under active investigation.

Animals↗
PubMed1990

Equine Culicoides hypersensitivity in Florida: biting midges aspirated from horses.

Nine species of Culicoides were aspirated from horses in Florida during the second phase of a study of equine Culicoides hypersensitivity (CHS). Approximately 90% of the 2933 midges were Culicoides insignis Lutz, 4% were C.stellifer (Coquillett), 3% were C.niger Root and Hoffman, 2% were C.alachua Jamnback and Wirth and the remaining 1% included C.venustus Hoffman, C.scanloni Wirth and Hubert, C.lahillei Iches (= C.debilipalpis Lutz), C.pusillus Lutz, and C.edeni Wirth and Blanton. Culicoides were sampled on seven farms located throughout Florida. The location and seasonality of lesion development on horses with CHS correlated with the Culicoides spp. collected directly from the horses as to their sites of attack, their seasonality and geographical distribution.

Animals↗
PubMed1990

Equine insect hypersensitivity: skin test and biopsy results correlated with clinical data.

Forty-four seasonally pruritic horses and 21 asymptomatic horses in Florida, USA, were tested for insect, grass and mould hypersensitivity by intradermal injection of allergenic extracts. The affected horses ranged in age from 10 months to over 30 years and included a variety of breeds. Affected horses reacted to varying dilutions of extracts made from Culicoides, mosquitoes, horse flies and black flies. Reactions to Culicoides were more intense than those caused by injection of antigens from other arthropods. Mild pruritus existed from the end of February until the end of June when the condition worsened and remained severe until November when it improved to an asymptomatic state. Histopathological examination of skin biopsies demonstrated changes compatible with arthropod hypersensitivity. Three clinical syndromes associated with insect hypersensitivity were described as follows: 1) horses with lesions on face, ears, mane, withers, rump and tail; 2) horses with lesions on face, ears, intermandibular space, chest, belly and groin, and 3) those with a combination of dorsal and ventral lesions.

Animals↗
PubMed1988

Familial allergic rhinitis in cattle.

A group of Angus X Holstein cattle were determined to have allergic rhinitis. Clinical signs included nasal discharge, tearing, sneezing, and nasal pruritus. The diagnosis was made on the basis of intradermal skin testing of affected and clinically normal cattle. The affected cattle had positive test results to various tree, grass, weed, and mold allergens. The clinical signs and seasonal occurrence were similar to those features for allergic rhinitis in man. Breeding data indicated an inherited mode of transmission, although only females were affected.

Animals↗
PubMed1988

Equine Culicoides hypersensitivity in Florida: biting midges collected in light traps near horses.

Twenty-three species of Culicoides were trapped near pruritic horses during a 2-year survey in Florida. Nearly 99% of the biting midges collected were represented by Culicoides insignis Lutz, C. edeni Wirth and Blandon, C. stellifer (Coquillett), C. niger Root and Hoffman, C. haematopotus Malloch and C. venustus Hoffman. The relative contribution to the total catch by each of these species varied among collection sites. Seasonally, different species attain their largest population sizes at different times. Association of species collected in light traps with the seasonality of lesion development on the horses suggests that more than one species must be involved in causing Culicoides hypersensitivity in horses from Florida. Nulliparous females were present in most months that females of the same species were active; in some cases, species were trapped in each month of the year, particularly at the more southerly sites. The species of biting midge most likely to be involved in Culicoides hypersensitivity in horses in Florida are C. insignis, C. stellifer and C. venustus based upon their mammalophilic behaviour and seasonality.

Animals↗
PubMed1987

Molluscum contagiosum in a horse with granulomatous enteritis.

Widespread cutaneous papules in a yearling Standardbred filly were attributed by light and electron microscopic examination to molluscum contagiosum. Concomitant granulomatous enteritis, suspected clinically due to protein-losing enteropathy, was verified histopathologically. An associated altered altered immune response is suggested as the reason for the widespread poxvirus infection.

Animals↗
PubMed1986

Responses of atopic dogs to regional allergens: 268 cases (1981-1984).

Responses of atopic dogs to intradermal challenge with 60 allergens were determined and compared for 4 regions of the United States Twenty-seven allergens incited significantly higher responses in atopic dogs residing in northern Florida, when compared with dogs in Illinois; responses to 28 allergens were more significant in dogs residing in southern Florida vs Illinois. Only 1 allergen caused more responses in atopic dogs in northern Florida, compared with dogs in southern Florida. Females had a higher tendency to develop clinical signs of atopy. Dogs of the West Highland White Terrier, Cairn Terrier, English Setter, Irish Setter, Dalmatian, Lhasa Apso, Golden Retriever, and Labrador Retriever breeds were found to be predisposed to develop clinical signs of atopy. Dogs of the Poodle, Pug, German Shepherd Dog, Cocker Spaniel, Bulldog, Schnauzer, Doberman Pinscher breeds, of mixed breeding, and of terrier breeds other than the 2 aforementioned were not found to have a higher prevalence, when compared with the general hospital population. Of the atopic dogs evaluated in Florida, 79% had a significant response to flea antigen, compared with only 9% of atopic dogs evaluated in Illinois.

Allergens↗
PubMed1986

Hyperprogesteronemia associated with Sertoli cell tumor and alopecia in a dog.

Hyperprogesteronemia was found in a dog with alopecia and Sertoli cell tumor. Alopecia began in the lumber areas; the entire coat was dull and dry, and epilated easily. The only laboratory abnormalities were high serum progesterone concentration and incomplete suppression of cortisol after low-dose dexamethasone administration. The hair regrew after castration, and the progesterone concentration decreased toward normal.

Adrenocorticotropic Hormone↗
PubMed1986

Treatment of canine idiopathic seborrhea with isotretinoin.

The efficacy and safety of isotretinoin in the treatment of idiopathic seborrhea in dogs were examined. Isotretinoin was judged effective in only 1 of 8 dogs. Side effects included mild conjunctivitis, transient erythematous rash, and increased serum cholesterol and triglyceride concentrations.

Animals↗
PubMed1984

Factors limiting the usefulness of histopathologic examination of skin biopsies in the diagnosis of large animal dermatoses.

Skin biopsy for histologic, immunofluorescent, parasitologic, and bacteriologic examination is a common procedure, but for maximum effectiveness the clinician must realize the importance of precautions to select the correct stage of lesion of different diseases; avoiding creating artifacts during removal and fixation; and give full details of history, clinical diagnosis, and differential diagnoses on the laboratory request sheet. Pathology reports describing the subtleties of histologic changes are difficult to write, particularly if the lesions are not specific. Overly long histologic reports without a definitive diagnosis may frustrate a clinician who is unfamiliar with the significance of histologic lesions. For these reasons, clinician and pathologist must develop a rapport and empathy for the other's difficulties and adequately communicate to allow each to make a maximum contribution toward the final diagnosis. Histopathologic examination of skin lesions may not produce a specific diagnosis but is frequently useful in the elimination of other suspected diagnoses.

Animals↗
PubMed1984

Canine and feline thyroid function assessment with the thyrotropin-releasing hormone response test.

A canine and feline pituitary-thyroid function test based on thyrotropin-releasing hormone (TRH) stimulation of endogenous thyrotropin is described. Serum thyroxine is measured before and after stimulation with TRH. A positive response to TRH indicated a functionally intact pituitary-thyroid axis. At TRH doses of 0.002 to 10.0 mg/kg of body weight, dose response of serum thyroxine to TRH stimulation was determined. Increasing the dose of TRH increased the duration, but not the magnitude, of thyroxine stimulation. At TRH doses greater than 0.1 mg/kg, drug side effects were salivation, defecation, urination, vomition, miosis, tachycardia, and tachypnea. A useful procedure for pituitary-thyroid function testing was serum thyroxine measurement before and 6 hours after TRH (0.1 mg/kg) stimulation.

Animals↗