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Biomedical subjects

B S Paul

Publications and source records attributed to B S Paul.

At least 19 recordsLinked to original sources
PubMed1983

The effect of temperature and other factors on selective microvascular damage caused by pulsed dye laser.

Brief pulses of 577-nm radiation have recently been shown to selectively damage superficial cutaneous blood vessels, resulting clinically in purpura. There was a sharp threshold of exposure dose necessary for causing purpura in any given subject, which correlated with histologic evidence of extravasation and specific vascular injury. As a means of studying mechanisms for such damage, heat, cold, pressure, suction, UV radiation, and intradermal epinephrine were used to alter human cutaneous microvasculature prior to and during 577-nm pulsed dye laser exposures. When compared with control sites, only cooling of the skin significantly affected the exposure dose needed to cause purpura. The magnitude of this effect is quantitatively most consistent with intravascular microvaporization as the cause of vessel rupture and hence purpura.

Coloring Agents↗
PubMed1983

Low-intensity selective UV phototherapy. A clinical trial in outpatient therapy for psoriasis.

A UV source of low-intensity output with peak effective emission in the 300 to 320-nm range, termed low-intensity selective UV phototherapy (LISUP), is being advocated for home phototherapy for psoriasis. Twenty patients with plaque-type psoriasis were treated three times a week as outpatients with this unit; the results were compared with those found in a similar group of 20 outpatients treated previously three times a week with a proved and effective protocol using erythemogenic exposures to a conventional UV-B source. Emollients were the only topical agents used during therapy. Eight patients had clearing and five others showed improvement with LISUP. Eighteen patients had clearing and one showed improvement with the UV-B protocol. We found LISUP less frequently effective when used three times a week in clearing plaque-type psoriasis. Therefore, we recommend a trial of this unit before purchase by the patient.

Adult↗
PubMed1983

Organelle-specific injury to melanin-containing cells in human skin by pulsed laser irradiation.

Physical models predict that ultraviolet laser radiation of appropriately brief pulses can selectively alter melanin-containing cellular targets in human skin. We exposed skin of normal human volunteers to brief (20 nanosecond) 351-nm wave length pulses from a XeF excimer laser, predicting that those cells containing the greatest quantities of melanized melanosomes (lower half of the epidermis) would be selectively damaged. Transmission electron microscopy revealed the earliest cellular alteration to be immediate disruption of melanosomes, both within melanocytes and basal keratinocytes. This disruption was dose dependent and culminated in striking degenerative changes in these cells. Superficial keratinocytes and Langerhans cells were not affected. We conclude that the XeF excimer laser is capable of organelle-specific injury to melanosomes. These findings may have important clinical implications in the treatment of both benign and malignant pigmented lesions by laser radiations of defined wave lengths and pulse durations.

Biopsy↗
PubMed1983

Pharmacokinetics and plasma protein binding (in vitro) of oxytetracycline in buffalo (Bubalus bubalis).

The pharmacokinetics of oxytetracycline given in a single dose (22 mg/kg) either IV or IM was studied in 4 female buffalo calves. The half-life (t1/2) after IV administration varied between 169.02 and 216.56 minutes and that after IM administration, between 630 and 990 minutes. The drug was distributed well in the body after IM administration (Vdarea 1.18 to 2.15 L/kg). The total body clearances varied between 1.02 and 1.45 and between 1.17 and 1.49 ml/kg/min after the IV and the Im dosings, respectively. It has been proposed that oxytetracycline is excreted mainly by glomerular filtration in the buffalo species, but tubular reabsorption also may have a small part. About 42% of the drug was bound to plasma proteins at concentrations of 2 to 20 micrograms of oxytetracycline/ml. The drug dosage schedules to maintain serum levels of 0.5, 1, 2, and 5 micrograms/ml also are determined.

Animals↗
PubMed1983

Treatment of pityriasis rosea with UV radiation.

Twenty patients with symptomatic and extensive pityriasis rosea were treated with unilateral UV-B phototherapy in a bilateral comparison study. Five consecutive daily erythemogenic exposures resulted in substantially decreased pruritus and extent of disease greater than that on the untreated side in approximately 50% of the patients. Therapy seems to be most beneficial to patients receiving treatment within the first week of the eruption.

Female↗
PubMed1982

Combined methotrexate--ultraviolet B therapy in the treatment of psoriasis.

Twenty-six patients with extensive psoriasis were treated with a 3-week course of methotrexate followed by a combination of ultraviolet B (UVB) therapy and methotrexate. A plaque of psoriasis was shielded during UV therapy to serve as a control. When lesions cleared to less than 5% of body involvement, the methotrexate was stopped and UVB therapy alone was used as maintenance therapy. This protocol achieved clearance of disease in all twenty-six patients in a mean of 7 (+/- 1.5) weeks, with twelve (+/- 4.0) exposures to UVB therapy and a final UVB radiation dose at clearance of 320 (+/- 157) mjoules/cm2. The mean total dose of methotrexate was 112 mg (range, 75 mg-165 mg). At the time of clearing, the shielded area had a decrease in sealing and thickness in twenty-two patients but was free of psoriasis in only four patients. In a preliminary study we were unable to reproduce a methotrexate recall of UV-induced erythema. The combination therapy of methotrexate and UVB allows for clearing of psoriasis at relatively low doses of UVB and methotrexate, and thus may reduce the long-term cumulative toxicity of both agents.

Adult↗
PubMed1982

The interaction of UVA and UVB in the production of threshold erythema.

A study was done to demonstrate quantitatively and graphically the way in which suberythemogenic doses of broadband UVA and UVB interact in producing a visible erythema. On the backs of fair-skinned human volunteers the minimal erythema dose (MED) was determined for polychromatic UVA and UVB. Increasing fractions of the UVA MED were given to sites already exposed to various fractions of the UVB MED resulting in sites exposed to various doses of both UVA and UVB. The same experiment was repeated with the order of wavebands reversed. It was demonstrated that when UVA was followed by UVB an erythema was produced in those sites where the sum of the fractions was equal to one, an interaction termed photoaddition. When the UVA exposure followed the UVB, erythema was again predominantly noted in those sites demonstrating photoaddition. However, in the latter case, numerous sites of threshold erythema were noted where the sum of the fractions was greater than one. This is suggestive of photorecovery. No evidence of photoaugmentation was observed with either order of exposure.

Erythema↗
PubMed1981

A study on renal function in the Indian buffalo (Bubalus bubalis).

Glomerular filtration rate (GFR) and effective renal plasma flow (ERPF) in buffalo species (Bubalus bubalis) were estimated using a single injection technique. The total body clearances of inulin and para-aminohippuric acid (PAH) served as estimates of GFR and ERPF, respectively. Inulin and PAH were administered to animals as a single i.v. bolus. The time-concentration curves were determined for each compound. Three mathematical models were applied to the data. The two compartment model gave the best fit to the data. The single compartment model gave slightly higher values, but could be used in clinical and certain research situations to estimate renal functions when it is not practical to take large number of samples.

Animals↗
PubMed1978

Influence of malathion (O,O'-dimethyl dithiophosphate of diethyl mercaptosuccinate) on body enzymes in dermal subacute toxicity studies in Bubalus bubalis species.

The effect of daily dermal spray of malathion for four weeks in recommended (0.5 and 1.0 per cent) and higher (5.0 per cent) concentration on various enzymes in Bubalus bubalis species were studied. The higher concentration of 5.0 per cent showed lethal effect after 2 to 3 exposures. The cholinesterase activity in both RBC (RChE) and plasma (PChE) were inhibited with all the concentrations. There was also significant (P less than 0.05) elevation in the activities of serum aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase with 1.0 and 5.0 per cent spray and enzyme activities remained altered even during post-medication. The extent of various biochemical changes were dose and time dependent.

Administration, Topical↗
PubMed1978

"No-effect-level" of malathion (o,o'-dimethyl dithiophosphate of diethyl mervaptosuccinate) in Bubalus bubalis.

An oral dose of 0.5 mg/kg/day malathion continuously administered for one year has been investigated to produce no change in biochemical (RChE, PChE, aspartate- and alanine aminotransferases, blood glucose, serum urea and plasma total proteins) or haematological (Hb, PCV, tRBC and tWBC) parameters and, therefore, considered to be "no-effect-level" in Bubalus bubalis. However, the administration of higher doses (1.0 and 1.5 mg/kg/day) produced significant (P less than 0.05) changes in all biochemical parameters studied. With these doses leucocytosis was evident among haematological parameters measured.

Animals↗