Location and length of arteriovenous fistulas around axial-pattern skin-flap pedicles.

The importance of the location of a surgically-created arteriovenous fistula around the pedicle (both distal and proximal) on the viability of rat skin flaps was investigated. The animals were randomly divided into four groups. Group 1 included bilateral standard island groin flaps. The right side flap was used as a control. On the left side, after elevation of the flap, an X-type arteriovenous fistula greater than 1 mm (up to 2 mm) in length was created distal to the pedicle, and just before the bifurcation of the common femoral vessels. In Group 2, the flap was an axial-pattern medially-based peninsular flap, including the same vessels. In this group also, two flaps were elevated bilaterally, and the right side was used as a control; on the left side, an X-type arteriovenous fistula the same length as in Group 1 was also created distal to the pedicle. In both groups, all other branches of the common femoral vessels were kept intact. In a second part of the study, two other animal groups were used to clarify the importance of the length of the arteriovenous fistula on the viability of skin flaps. In Group 3, the model was the same as in Group 1, but the fistula was 1 mm in length. In Group 4, the length of the fistula was 1 mm, and its location was on the common femoral vessels proximal to the pedicle, using the same flap model. Flow values were measured repeatedly using a laser Doppler flowmeter. Histopathologic studies were also done. There are three important points arising from these studies. 1). The location of an X-type arteriovenous fistula around an island skin flap pedicle seems to be more important than diameter. An arteriovenous fistula proximal to the pedicle is more hazardous than an arteriovenous fistula distal to the pedicle, regarding island skin-flap viability. 2). However, the length of the fistula is also important, and an arteriovenous fistula distal to the pedicle, with a sufficiently long length, is not devoid of harmful effects. It is also clear that the larger the fistula, the greater the systemic effects. 3). An island skin flap with an arteriovenous fistula distal to its pedicle might be a useful model to study the relationship between skin-flap viability and edema formation.

The brain and other sites of erythropoietin production.

Ischemic hypoxia of the head induced in dogs by carotid compression produces EPO secretion, upon direct cerebral stimulation, and adaptive carotid-respiratory reflexes via sino-carotid stimulation. During hypoxic hypoxia, there also occurs extrarenal EPO production, as shown in binephrectomized rats compared to controls. Ischemic hypoxia of a single kidney transplanted in the neck area (the other kidney being removed) does not induce EPO secretion. An additional factor, of extra-renal origin, is required for the renal production of EPO in a non-hypoxic organism. Section of the spinal cord at C6 level in rats does not abolish EPO secretion induced by hypobaric hypoxia, a fact that suggests that there is no nervous center to control EPO release into a peripheral organ, but EPO might be produced in the brain itself, possibly crossing the blood-brain barrier to reach the blood flow. Stereotactical attempts to locate nervous centers of erythropoiesis regulation also failed. EPO secretion obtained by electrical stimulation of different brain areas suggests the existence of widespread secretory cells, which might be the astrocytes. EPO production along the lymph-forming territories and the involvement of the lining macrophages is reported.

[Marjolin's ulcer on burn scar, a curable but neglected disease]. / Ulcerul Marjolin dezvoltat pe cicatrici postcombustionale--afectiune vindecabila, dar neglijata.

We discuss 9 consecutive carcinomas developed on postburn scars. Our interest was focused on surgery, recurrence, metastasis and long-term survival. The delay between burn trauma and the first clinical manifestation was 25-63 years. The most common localisation was in the limbs (10). Two cases presented with visceral metastasis. We performed either wide excision and grafting (5) or amputation (5). From the anatomo-pathological stand point we encountered 8 SCC and 1 BCC. In 6 cases we had no local recidive or metastasis. One presented a local recidive. There were two deaths--lung metastasis and "spontaneous" rupture of invaded axillary artery. The Marjolin's ulcer has a low incidence because of the patient's poor education. The prophylactic attitude is optimal. We favour early excision--grafting of the deep burns, long-term follow-up, excision and grafting of unstable areas (joint area, depigmented regions, chronic ulcers). The optimal surgical technique is excision followed by skin grafting since it allows early detection of the recurrence.

Circadian rhythm of phagocytosis in mice.

There has been reported, in some diurnal or equivocal species (man, respectively guinea pig), a circadian rhythm of the phagocytic activity of blood neutrophils, with an acrophase occurring at the end of the light span. The present study, carried out on NMRI adult male mice kept on a LD 12:12 regimen, aimed to assess any circadian variation in the blood neutrophils' phagocytosis level. Basal phagocytic activity was tested against E. coli, every three hours of a 24 h cycle. The results show that phagocytosis in mice's blood neutrophils also presents a rhythmic circadian variation, whose acrophase is delayed with about eight hours compared to that in man, occurring in the second half of the dark period (3:00 h). The occurrence of high circadian phagocytic levels appears to be correlated with the activity type of the species and, of this point of view, mice cannot be used as a model for chronotherapeutical approaches in humans, without keeping in mind the differences between the time structure of the two species.

Influence of bilateral olfactory bulbectomy on the circadian rhythm of phagocytic activity and phagocytic response in mice.

The bilateral olfactory bulbectomy (OB) has been proposed as an animal model of depression. The present study, carried out on NMRI adult male mice kept on a natural LD 12:12 regimen, aimed to assess the influence of OB on the circadian rhythm of blood neutrophils phagocytosis. The results show that OB mice present an about 20% reduction of the basal phagocytic activity at 09.00 hrs, 15.00 hrs. and 21.00 hrs. and a 40% reduction at 03.00 hrs., leading to a flattened circadian phagocytic curve. The results indicate that bilateral olfactory bulbectomy depresses phagocytosis, alters its circadian rhythm and consequently increases susceptibility to infections.

Effects of monosodium glutamate on blood neutrophils phagocytic activity and phagocytic response in mice.

Previous researches of our laboratories (1945, 1946, 1947) have shown that direct electrical stimulation of the tubero-mammillary hypothalamic area in dogs enhances the blood neutrophils phagocytic activity and the phagocytosis exhibiting leukocytes percent. After electrolytic damage of the same area, phagocytic activity decreases and phagocytic response is suppressed (1985, 1988). In the present work, we performed in mice extensive chemical lesions of the arcuate nucleus, by means of the neonatal treatment with monosodium glutamate (MSG). The experiment was carried out on 23 new-born mice. 15 mice were injected with MSG (G group), the other 8, serving as control group, received isotonic saline solution (C group). The studied parameters were, in both groups, the weight evolution of the animals, the blood neutrophils and lymphocytes percentual variation and the neutrophils' phagocytic activity, tested in vitro, expressed through the number of bacteria engulfed by 100 neutrophils and through the phagocyting neutrophils percentage. Phagocytic activity was tested in whole heparinised blood, against E. coli. Phagocytic response was elicited by i.p. injecting 0.05 ml bacterial suspension and was tested four hours later. The results show that the arcuate nucleus has little influence upon maintaining basal phagocytic activity--that does not significantly decrease after its chemical damage--, but plays a decisive role in triggering the phagocytic response. The neonatal MSG treatment also determines a decrease of the blood lymphocytes percentage and induces obesity in up to 30 days old mice pups.