30 September 2009

Immunoassays



Immunoassays
By:Diane C. Jette, Ph.D.
BioMedica Diagnostics Inc.

Test Menu
* Infectious Diseases
* Cardiac Markers
* Cancer Screening
* Fertility / Hormones
* Drugs of Abuse
* Other Tests
o IgE
o Rh Factor
o Occult Blood
o TSH, T3, T4
o Blood Grouping

Test Formats Available
* Latex Agglutination
* DIPSTICK
* Card Format
* Cartridge Format
* ELISA Format with Plate Reader

Structure of IgG
(150,000 Daltons)
Antigen
Binding Site
Fab
Fc

Structure of IgM
(900,000 Daltons)
Binding Sites
Sandwich ELISA Procedure
* Antibody coated on plate.
* Incubate with sample containing antigen.
* Wash away unbound material.
* Incubate with antibody-enzyme conjugate.
* Wash away unbound conjugate.
* Add substrate.
* Enzyme acts on substrate and produces color change.
* Measure amount of color produced.
* Amount of antigen present is proportional to the amount of color produced.

ELISA: Sandwich Format
Sandwich Assay Results
Color Intensity (OD)
Antigen Concentration
Linear Range
ELISA: Inhibition Assay Procedure

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Urine Analysis



Urine Analysis
By:Diane C. Jette, Ph.D.
BioMedica Diagnostics Inc.


Reagent Test Strips
* Multiple test reagents on a ready to use test strip.
* Test results are read at different times after brief exposure to urine sample.
* The color on strip is compared to the reference color shown on test strip packaging.

Typical Test Strip Test
Glucose
Bilirubin
Ketone
Blood
Protein
Nitrite
Leukocytes
pH
Specific Gravity
Urobilinogen
Sensitivity_
* 4 to 7 mmol/L
* 7 to 14 mol/L
* 0.5 to 1.0 mmol/L (Acetoacetic acid)
* 150 to 620 g/L (Hemoglobin)
* 0.15 to 0.3 g/L (Albumin)
* 13 to 22 mol/L
* 5 to 15 cells/ L
* pH 5.0 to 8.5
* 1.000 to1.030
* 0.2 to 8 mol/L

Glucose
* Small amounts of glucose normally excreted by the kidney.
* Below sensitivity of the test.
* >6 mmol/L clinically significant.

Bilirubin

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29 September 2009

Andrews’ Diseases of the Skin



Andrews’ Diseases of the Skin
By:Boris Ioffe, D.O.

Recalcitrant Palmoplantar Eruptions

* Recalcitrant pustular eruptions of the hands and feet are often examples of psoriasis
* Need to then search for lesions elsewhere on the body(e.g., scalp, ears, glans penis)
* Search also for a family history to confirm your suspicion

Dermatitis Repens
* Aka- acrodermatitis continua and acrodermatits perstans
* It’s a chronic inflammatory disease of hands and feet
* Rarely, can become generalized
* Usually, as a pustule or paronychia
* Occasionally, mucous membranes are involved
* Nails are often dystrophic or destroyed
* Lesions cause skin atrophy
* Crusted, eczematoid, and psoriasiform lesions may occur, and there may be moderate itching
* It is essentially unilateral in its beginning and asymmetrical throughout its entire course
* Histology
o similar to those seen in psoriasis
o the primary lesion is epidermal
o An intraepithelial spongiform pustule is formed by infiltration of pmn’s
* Treatment
o topical mechlorethamine, topical steroids, PUVA, fluorouracil, and sulfapyridine
o Acitretin, low dose cyclosporine, Acitretin plus calcipotriol

Palmoplantar Pustulosis
* AKA pustular psoriasis
* In contrast to dermatitis repens it is essentially bilateral and symmetrical
* Locations include: thenar/hypothenar eminences or central portion of the palms and soles
* Patches begin as erythematous areas in which pustules form
* Start as pinhead-sized, enlarge and coalesce to form small lakes of pus
* In the course of a week, they tend to dry up, leaving punctate brown scabs that eventually exfoliate
* Stages of quiescence and exacerbation characterize the condition
* Meds, such as lithium, have been reported to induce
* Nails may become malformed, ridged, stippled, pitted and discolored
* May be associated with psoriasis vulgaris
* Some regard palmoplantar pustulosis as a form of psoriasis, while others consider it a separate entity
* Female predominance; lack of seasonal variation; different histopathologic features and
* Associated with thyroid disorders and cigarette smoking
* May be predisposed to joint disease and possibly SAPHO syndrome-Synovitis, Acne, Pustulosis, Hyperostosis and Osteoarthritis
* It’s resistant to most treatments
* Acitretin is reportedly effective(1mg/kg/day)
* Low-dose cyclosporine (1.25mg/kg/day-3.75mg/kg/day)
* Intramuscular Kenalog (40-60mg)may be effective for short-term relief

Pustular Bacterid
* Characterized by a symmetric, grouped, vesicular or pustular eruption on palms and soles
* Marked by exacerbations and remissions over long periods
* No involvement of webs of fingers or toes or flexion creases of toes
* WBC may be elevated
* Scaling is usually present
* Etiology is thought to be a remote focus of infection; infection needs to be treated before resolution will occur

Juvenile Plantar Dermatosis
* Usually begins as a patchy, symmetrical, smooth, red, glazed macule on great toes, sometimes with fissuring and desquamation in children aged 3-13
* Toe webs are rarely involved; fingers may be
* Histologically, there is psoriasiform acanthosis and a sparse, lymphocytic infiltrate in the upper dermis
* Spongiosis is commonly present
* Tx: bed rest, cotton socks and topical steroids
* Spontaneous resolution within 4 yrs is the rule

Infantile Acropustulosis
* Intensely itchy vesicopustular eruption of hands and feet
* Begins at any age up to 10 months, clearing in a few weeks and recurring repeatedly until final resolution at 6 – 36 months of age
* Dapsone at 2mg/kg/day may help
* Potent topical steroids aid in symptomatic relief
* Should prompt an extensive workup to eliminate serious infectious causes (i.e., Tzanck prep, gram stain, KOH prep of pustule)
* Some suspect that this condition may be a persistent reaction to prior scabies

Infantile Acropustulosis
* Acropustulosis of infancy
Pompholyx
* AKA dyshidrosis
* A vesicular eruption of palms and soles characterized by spongiotic intraepidermal vesicles and often accompanied by burning or itching
* Hyperhidrosis may be present
* Usually bilateral and symmetrical
* Bullae may form
* Contents are clear and colorless
* Attacks generally last a few weeks
* Lesions dry-up and desquamate rather than rupture
* Etiology- stress, atopy, and topical as well as ingested contactants
* Histopathology: spongiotic vesicles in the epidermis
* Differential dx:
o dermatophytid, contact dermatitis, atopic dermatitis, drug eruption, pustular psoriasis of palms and soles, acrodermatitis continua, and pustular bacterid
* Rarely, T-cell lymphoma can present with similar clinical findings, but biopsy of the vesicles will be diagnostic
* Tx: high potency corticosteroid creams
* Triamcinolone acetonide intramuscularly or a short course of oral prednisone is rapidly effective
* Oral or topical psoralen + UVA (PUVA) is effective but costly & inconvenient
* In more severe forms, immunosuppressive mycophenolate mofetil has been effective

Lamellar Dyshidrosis
* AKA dyshidrosis lamellosa, keratolysis exfoliativa
* A superficial exfoliative dermatosis of the palms and sometimes soles
* Referred to as recurrent palmar peeling
* Involvement is bilateral
* Can occur in association with dyshidrosis
* Often exacerbated by environmental factors
* Differential dx: dermatophytosis, chronic contact dermatitis
* Tx: difficult
* Spontaneous involution can occur in a few weeks for some
* Most tends to be chronic and relapsing
* Tar creams (Zetone cream) usually helps
* 5% tar in gel (Estar Gel) is an excellent tx
* Lac-Hydrin lotion and Carmol 10 or 20 are often effective
* NB-UVB may be helpful

Palmoplantar Keratoderma
* AKA tylosis, keratosis, hyperkeratosis
* Characterized by excessive formation of keratin on the palms and soles
* Acquired
o Keratosis Punctata of the Palmar Creases
o Punctate Keratoses of the Palms and Soles
o Porokeratosis Plantaris Discreta
o Keratoderma Climactericum
* Congenital


Punctate Keratosis of the Palms and Soles
* Primary lesion is a 1-5mm round to oval, dome-shaped papule distributed over left hand and hypothenar eminence
* Main symptom is pruritis
* Lesions number from 1 to >40
* Affects mainly blacks
* There’s a potential risk of developing lung and colon cancer

Keratosis Punctata of the Palmar Creases
* Common most often in black pts
* Primary lesion is a 1-5mm depression filled with a conical keratinous plug
* Primarily, in creases of palms or fingers, occasionally in soles
* Lesions are multiple
* Friction aggravates lesions causing them to become verrucoid or surrounded by callus
* Punctate keratoses of the palmar creases in an African-American
* PPPK-punctate palmoplantar keratoderma

Porokeratosis Plantaris Discreta
* Occurs in adults, Female:Male (4:1)
* Characterized by sharply marginated, rubbery, wide-based papule that does not bleed on removal
* Lesions are multiple, painful, 7-10mm in diameter
* Usually on wt bearing areas of sole, beneath metatarsal heads
* Tx: foot pads to redistribute wt, surgical excision, blunt dissection

Keratoderma Climactericum
* Characterized by hyperkeratosis of palms and soles beginning at about the time of menopause
* Descrete, thickened, hyperkeratotic patches most pronounced at pressure sites
* Fissuring may be present
* Tx: keratolytics -- 10% salicylic acid, lactic acid creams, etc.

Hereditary syndromes
* These have palmoplantar keratoderma as a feature
o Unna-Thost
o Papillon-Leferve
* Dominant inheritance; congenital thickening of epidermal horny layer of the palms and soles
* Usually symmetrical
* Epidermis becomes thick, yellowish, verrucous, and horny
* Striate and punctate forms occur

Unna Thost
* Occasionally nails become thickened
* 5% salicylic acid may help
* Lac Hydrin 12% may be tried
* Acitretrin or isotretinoin may be considered, but need for lifetime tx makes them impractical
* Focal palmoplantar keratosis of the striate type on the sole
* Diffuse non-epidermolytic palmoplantar keratosis
* Diffuse epidermolytic palmoplantar keratosis with diffuse hyperkeratosis

Papillon-Lefevre Syndrome
* Palmoplantar hyperkeratosis with peridontosis
* Usually develops within the first few months of life but may occur in childhood
* Well demarcated, erythematous, hyperkeratotic lesions on palms and soles
* Transverse grooves of fingernails may occur
* Early onset peridontal disease has been attributed to damage and alteration in PMN function caused by Actinomyces actinomycetemcomitans
* Disease associations include: acroosteolysis, and pyogenic liver abcesses
* There are asymptomatic ectopic calcifications in the choroid plexus and tentorium
* Therapy may retard both dental and skin abnormalities
* Treatment with Acitretin in four siblings was reported to be effective

Papillon-Lefevre Syndrome
* Papillon-Lefevre syndrome: plantar keratoderma

Mutilating Keratoderma of Vohwinkel
* Palmoplantar hyperkeratosis of the honeycomb type-associated with starfish-like keratosis on backs of hands and feet; linear keratoses of the elbows and knees, and annular constriction (pseudo-ainhum) of the digits, this may progress to autoamputation
* More than 30 cases have been reported world-wide
* More common in women and in whites
* Onset is in infancy or early childhood
* Vohwinkel’s mutilating syndrome: A.) diffuse keratoderma of palms with B.) pseudoaainhum formation

Palmoplantar Keratodermas & Malignancy
* Diffuse, waxy keratoderma of palms and soles occurring as an AD trait associated with esophageal carcinoma
* Other related factors are oral leukoplakia, esophageal srictures, squamous carcinoma of tylotic skin, carcinoma of larynx and stomach
* Acquired forms of palmoplantar keratodermas have also been associated with carcinoma of esophagus, lung, breast, bladder and stomach
* Focal PPK in association with carcinoma of the esophagus

Acrokeratoelastoidosis of Costa

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