Studies of herpes virus latency in the sensory spinal ganglia of rabbits

Experimental latent herpes infection of rabbit dorsal root ganglia (DRG) is reported. The simian herpes virus used was derived from fatal natural infection in owl monkeys and has limited neurotropism in the rabbit. Following intradermal injection of the flank it causes a local lesion followed only by dorsal root ganglionitis; segmental paraesthesia and/or sensory loss going on to clinical recovery. Methods were developed for mapping sensory losses. Virus could be immediately re-isolated from skin or DRG homogenates in the acute (first week) stage but from 8-550 days by DRG organ culture only. Spontaneous recurrence does not occur but reactivation can be provoked. The system provides an improved analogue model for the study of the pathogenesis and symptomatic treatment of herpes zoster.

In vivo and in vitro development of serotonergic neurons

The monoamines are one of the earliest developing neurotransmitter systems in the mammalian brain. The first part of this paper describes the normal ontogeny of the serotonergic (5-HT) system in the rat brain as studied using long survival 3H-thymidine autoradiography (time of neuronal genesis, time of origin) and the Falck-Hillarp histofluorescence method, electron microscopy, and immunocytochemistry (anti-5-HT). Due to their early ontogeny relative to other brain regions, 5-HT neurons (as well as monoamine neurons in general) have been suggested to exert some type of "trophic" influence on brain development. Results of pharmacological experiments designed to inhibit 5-HT synthesis in the embryonic rat brain by maternal treatment with p-chlorophenylalanine (pCPA) at a time when this monoamine might exert such an influence are discussed with regard to effects on the time course of neuronal genesis (time of origin) of 5-HT neurons and their target cells. These results, which prompted us to propose that 5-HT might act as a "differentiation signal" for certain of its target cells, are now discussed in light of our more recent immunocytochemical-autoradiographic studies (anti-5-HT, 3H-thymidine) which morphologically demonstrate close associations between developing 5-HT neurons and proliferating neuroepithelial cells in the embryonic brain. Postnatal studies using this immunocytochemical-autoradiographic method also provide evidence for interactions of 5-HT axons with proliferating glioblasts in the developing cerebellum and with immature granule cells and their precursors in the hippocampus. These findings, in conjunction with the results of our pCPA experiments, further enhance the possibility that 5-HT neurons could exert an epigenetic influence on the development of less differentiated cells with which they come into contact. Finally, preliminary studies using dissociated cell cultures containing 5-HT neurons suggest that interactions between 5-HT neurons and glial elements may be important for the differentiation of these neurons in vitro. Whether 5-HT neurons in turn influence the development of glial or neuronal cells in these cultures remains to be determined. These studies are evaluated with regard to a possible pre-transmission role for 5-HT during key phases of neuronal and glial genesis.

Protein synthesis-dependent and protein synthesis-independent secretion of lysosomal hydrolases from rabbit and human macrophages

Rabbit alveolar macrophages and human monocyte-derived macrophages released lysosomal enzymes in response to a variety of stimuli. The release of these enzyme appeared to be under the control of at least two distinct mechanisms. The first involved a rapid release of preformed granule constituents in response to a phagocytic load. This release reaction was concentration- and time-dependent, was not affected by the protein synthesis inhibitors cycloheximide and puromycin, and resulted in a concomitant loss in intracellular enzyme levels. The second mechanism involved a prolonged secretion in response to lower concentration of stimuli, which increased with time, and was inhibited by cycloheximide and puromycin. The secretion did not result in the loss of intracellular enzyme stores; rather an induction of enzyme was seen following such stimulation, which resulted in increases in the total concentration within the cultures. This protein synthesis-dependent secretion of acid hydrolases from human macrophages varied for each lysosomal hydrolase and each stimulus. beta-Glucosaminidase synthesis and secretion was induced by low-dose opsonized zymosan, by latex particles, and by formaldehyde-treated SRBC. However, only the last mentioned stimulus caused release of acid phosphates although all three particles induced synthesis of the enzyme. None of the stimuli at these concentrations (10:1 particle to cell ratio) caused the release of beta-glucoronidase, although the enzyme was releasable if higher stimulus concentrations were used. In addition the enzyme was not inducible under these conditions. It is concluded that each of the acid hydrolases studied may be under different control in the human macrophage and that the cells may respond in a qualitatively different way to different types of phagocytosable stimuli.

A differential effect of C5a and C5a des Arg in the induction of pulmonary inflammation

Earlier studies have shown that C5 fragments induce an inflammatory reaction when instilled into the rabbit lung. Because C5a is rapidly converted to C5a des Arg in vivo, experiments were performed to determine which fragment was most effective in producing pulmonary inflammation in this animal model. C5a des Arg consistently produced marked inflammation. This was characterized by neutrophil accumulation, edema, hemorrhage, fibrin formation, and damage to alveolar epithelium. The time course of the inflammatory reaction initiated by C5a des Arg showed pulmonary vascular sequestration of neutrophils with no intra-alveolar migration at 30 minutes after injection. By 2 hours, interstitial and alveolar neutrophils were numerous, with the accumulation of neutrophils in the alveoli increasing to a maximum at 6 hours. At 24 and 48 hours, the predominant cells were mononuclear (macrophages). By 120 hours, the lesions were resolving. In contrast, at all doses examined, a similar instillation of C5a induced either no inflammation or a milder, more focal response than C5a des Arg. This inability of C5a to initiate inflammation was not apparently due to the generation of inhibitors, since mixtures of C5a and C5a des Arg were phlogistic. A prolonged, intrapulmonary infusion of C5a (20 minutes), in contrast to a bolus instillation (1 minute), did initiate an inflammatory response, which may reflect the conversion of the C5a to C5a des Arg in the lung. This study points out the inflammatory potential of products of complement activation, particularly of the C5 fragment C5a des Arg, when applied to the airway side of the lungs. This inflammatory response raises the possibility that cleavage of intrapulmonary C5 may play an important role in the initiation of pulmonary inflammation.

Induction of lysosomal enzyme secretion by alveolar macrophages in response to the purified complement fragments C5a and C5a des-arg

Purified C5a and its "inactive" form, C5a des-arg, were shown to induce secretion of acid hydrolases from rabbit alveolar macrophages (AM) in a concentration-dependent manner. Secretion increased with time to 5 times above controls by 72 hr. Concentrations of these enzymes in the cell lysates did not decrease during the incubation, suggesting that synthesis of new enzyme was occurring. The lysosomal enzyme secretion was accompanied by increased pinocytosis and release of proteolytic enzymes from the macrophages. At no time was significant lactic dehydrogenase liberated, indicating that secretion was selective and not due to cell death. Data presented also suggest that C5a des-arg induced secretion from the macrophages of a chemotactic factor for neutrophils. It was concluded that C5a and C5a des-arg may play a role in lung injury by interactions with AM, inducing the secretion of acid hydrolases and proteolytic enzymes that can cause tissue damage, and by regulating the influx of other inflammatory cells into the interstitium and air spaces.

Complement fragments, alveolar macrophages, and alveolitis

Mechanisms of neutrophil infiltration into the rabbit alveolus have been investigated. Complement activation in the circulation induced pulmonary vascular margination but not a significant level of alveolar infiltration. Instillation of C5 fragments into the airways, however, attracted neutrophils into the alveolar airspaces. The anaphylatoxin-inactive fragment of C5, C5a des Arg, was found to be much more active in this regard than C5a. Furthermore, these fragments were shown to induce the production of a neutrophil-directed chemoctactic factor from pulmonary macrophages, raising the question of whether the C5a des Arg was acting directly to attract neutrophils or indirectly via the macrophage. To substantiate a possible role for C5 and C5 fragments in alveolitis, active C5 was demonstrated in lavage fluids, and macrophage-derived C5 cleaving enzymes have been described. Finally, a route of neutrophil infiltration via migration through the alveolar capillary wall into the interstitium is proposed, and subsequent penetration of the alveolar epithelium out into the airspace. (Am J Pathol 97:93--110, 1979).

Observations of the effects of formaldehyde on cockroaches and their flora: III. The effect of formaldehyde in eliminating the normal gut flora

The normal flora of cockroaches (Periplaneta americana) was determined over a period of 24 days prior to substituting water with 1% Formalin for drinking water. During the first 4 days of treatment the normal flora was significantly reduced and by the fifth day, when the cockroaches became diarrhoeic, no bacteria, fungi, or viruses could be detected by the methods used.

Observations on the effects of formaldehyde on cockroaches and their flora: II. Prolonged survival of cockroaches drinking formaldehyde or glutaraldehyde solutions

Adult cockroaches were found to survive up to 22 weeks when provided with 1% Formalin (0.4% formaldehyde) in lieu of drinking water. Given 4% Formalin or 2% glutaraldehyde they survived up to 41 days. During the experiments eggs were laid and hatched and the offspring continued to grow. Combined with surface disinfection, this may hold out a simple method of rendering adult cockroaches gnotobiotic or even axenic.

Observations on the effects of formaldehyde on cockroaches and their flora: I. Survival of vaccinia virus-infected cockroaches during fumigation with formaldehyde

In these studies it is shown that the common "British" and "American" adult cockroaches can survive exposure to formaldehyde fumigation carried out at double the strength and for four times as long as is recommended for disinfection of rooms. It is further reported that vaccinia virus ingested prior to the fumigation survives in the cockroach gut and may be excreted up to 5 days later. Since cockroaches are ubiquitous and are to be found in most hospitals, laboratories and animal houses, these findings should be considered whenever fumigation is called for.

Adolescent breast masses

A retrospective experience with breast masses in 143 female and 22 male adolescents is reviewed: 104 females (71.7 per cent) had fibroadenomas and 1 (0.7 per cent) adenocarcinoma; all 22 males had gynecomastia. The significance of these findings is related to surgical therapy.

Hazards from simian herpes viruses: reactivation of skin lesions with virus shedding

A new simian herpes virus with biological properties similar to herpes simplex and to simian "B" virus has been used as a model system for studying virus latency in dorsal root spinal sensory ganglia. Following intradermal injection, virus is present in the skin lesions and corresponding ganglia only, during the acute stage of the disease. By organ-culture techniques, latent virus was rescued from ganglia up to 2 years later. No latent virus was ever found in skin organ cultures of the primary site. Treatment with cortisone up to 18 months later reactivated virus latent in the ganglia, and virus returned to the skin where it produced small but typical herpes lesions which shed virus. Reactivation of Herpesvirus tamarinus was achieved after 28 months. This is believed to be the first report of a model system for the study of herpes latency in which skin lesions are found to recur, and provides an opportunity for more detailed investigations of the mechanisms of virus latency in man. The presumption that reactivation of skin lesions will also be possible in rhesus monkeys seropositive for "B" virus points to a possibly grave and largely unsuspected hazard for those engaged in primate research.