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Biomedical subjects

S G Allen

Publications and source records attributed to S G Allen.

27 records · Page 2Linked to original sources
PubMed1989

Lack of host cellular immune response in eruptive molluscum contagiosum.

A lack of cellular immunity on the part of the host has been incriminated as the cause of the persistence of the cutaneous lesions of molluscum contagiosum. We present a patient in the eruptive phase of the disease, confirming the absence of T-lymphocyte and natural killer cell subsets in the base of these typical lesions, using a panel of monoclonal antibodies. We also report the observation of lipid material ultrastructurally (confirmed by osmium staining on fresh-frozen tissue), as well as cross-reactivity immunocytochemically of the antigens on these molluscum bodies with antigens normally present on macrophages, as defined by DAKO-macrophage monoclonal antibodies. We have considered the possible role of these findings in the lack of host cellular responsiveness in the eruptive phase of the disease.

Adult↗
PubMed1989

An electron microscopic study of the epidermal infiltrate in recurrent herpes simplex.

Host immunity has been suspected of playing a role in recurrent herpes simplex. In this preliminary ultrastructural study of two patients with acute herpetic eruption, it was noted that the keratinocytes exhibiting the most severe damage are those adjacent to large granular lymphocytes. In contrast, many keratinocytes filled with viral particles of herpes simplex show little or no signs of keratinocyte damage. These observations suggest that in recurrent herpes simplex the epidermal damage may be due, at least in part, to cell-mediated host immunity as well as to the viral infection.

Adult↗
PubMed1988

High endothelial venules in involved and uninvolved psoriatic skin: recognition by homing receptors on cytotoxic T lymphocytes.

We report the presence of tannic acid staining material in the intercellular spaces between adjacent endothelial cells of the high endothelial venules (HEVs) in psoriatic skin, which appears to be recognized by T8 (cytotoxic/suppressor) lymphocytes, as the presence of HEVs was found to be related to the presence of T8 lymphocytes in the epidermis. As HEVs with similar tannic acid staining material were also observed in peripheral lymph nodes, we suggest that this material may serve as a marker for HEVs recognized by the T8 lymphocyte subset. T8 + lymphocytes were found in the epidermis at 5 min and I h after tape-stripping of uninvolved skin of psoriatic patients with active disease, but not until 24 h in a psoriatic patient in remission. The prior existence of HEVs in uninvolved psoriatic skin could account for the rapid egress of T8 lymphocytes from the vasculature to the epidermis in response to trauma.

Antibodies, Monoclonal↗
PubMed1987

Electron microscopic features in generalized pustular psoriasis.

Basal keratinocyte herniations (BKH) have been used as markers of psoriatic activity. Abnormal multipolypoid forms herniating through large gaps in the basal lamina have been found to characterize biopsies from psoriatic patients with concomitant alpha 1-antitrypsin deficiency, and appear to be a marker of excessive proteolytic activity. The finding of similar multipolypoid BKH in patients with generalized pustular psoriasis of the von Zumbusch variety (but not in patients with psoriasis vulgaris), in the absence of concomitant alpha 1-antitrypsin deficiency, would support the concept of the presence of large amounts of proteolytic enzymes in the dermis of patients with this syndrome. The large proportion of BKH directly associated with dermal neutrophils, and the presence of clusters of high-density BKH overlying collections of dermal neutrophils, suggests that neutrophilic proteases are largely responsible for BKH formation in patients with this syndrome.

Adult↗
PubMedDate not supplied

The frequency of postdural puncture headache in obstetric patients: a prospective study comparing the 24-gauge versus the 22-gauge Sprotte needle.

STUDY OBJECTIVE: To compare the frequency of postdural puncture headache (PDPH) in obstetric patients when using the 24-gauge or the larger 22-gauge Sprotte needle. DESIGN: Prospective, randomized study. SETTING: Four hospitals. PATIENTS: 375 ASA physical status I and II cesarean section and postpartum tubal ligation patients. INTERVENTIONS: Obstetric patients were randomly assigned to receive spinal anesthesia via a midline dural puncture using the 24-gauge or the 22-gauge Sprotte needle. MEASUREMENTS AND MAIN RESULTS: The rate of PDPH was determined by a postoperative visit by the anesthesiologist as well as questioning patients by telephone 1 week or more after discharge. In the 24-gauge Sprotte needle group (n = 186), 2 mild and 1 moderate PDPHs were reported, for an overall rate of 1.61%. In the 22-gauge Sprotte needle group (n = 189), 2 mild and 1 moderate PDPHs were reported, for an overall rate of 1.59%. All headaches except 1 resolved within 72 hours with conservative treatment. One patient from the 22-gauge Sprotte needle group required an epidural blood patch. There were no failed blocks in either group. CONCLUSIONS: Our results suggest that the 22-gauge Sprotte needle, when compared with the smaller 24-gauge Sprotte needle, can be used in obstetric patients without increasing the frequency of PDPH.

Adult↗
PubMedDate not supplied

Diffusion processes in confined materials.

The diffusion coefficient for cyclohexane confined within pores of diameter 40 to 500 A has been measured as a function of temperature between 296 and 180 K, and is compared to values obtained for the bulk material. A substantial liquid-like signal is observed in the region of the depressed freezing points and a diffusion coefficient is measurable in all samples to well below these temperatures. The diffusion data appear to be continuous over the freezing region. These observations suggest persisting molten layers at interfaces which exchange with crystals forming within the silica pores. The diffusion coefficient of the molecules in the surface layer is three orders of magnitude larger than in the plastic phase of bulk cyclohexane.

Cyclohexanes↗