Fatal cervical necrotizing fasciitis (a report of two cases of confirmed odontogenic origin and one of possible odontogenic origin).

Three cases of cervical necrotizing fasciitis (CNF), two of confirmed odontogenic origin and one of probable odontogenic origin, were observed from 1993-1999. This is in addition to three cases previously reported by this office. A rare sequelae of dental infection, CNF can be a severe, rapidly progressing infection of the cervical tissues having a mortality rate of up to 50%. "Hospital gangrene" was first described during the Civil War. It was later to be described as necrotizing fasciitis and later yet was designated as a separate clinicopathological diagnosis.

Learned discrimination of pattern orientation in walking flies.

To determine the pattern-orientation discrimination ability of blowflies, Phaenicia sericata, a learning/memory assay was developed in which sucrose served as the reward stimulus and was paired with one of two visual gratings of different orientations. Individual, freely walking flies with clipped wings were trained to discriminate between pairs of visual patterns presented in the vertical plane. During training trials, individual flies learned to search preferentially at the rewarded stimulus. In subsequent testing trials, flies continued to exhibit a learned preference for the previously rewarded stimulus, demonstrating an ability to discriminate between the two visual cues. Flies learned to discriminate between horizontal and vertical gratings, +45 degrees (relative to a 0 degrees vertical) and -45 degrees gratings, and vertical and +5 degrees gratings. Individual patterns of learning and locomotive behavior were observed in the pattern of exploration during training trials. The features of the visual cue critical for discrimination of orientation are discussed.

Orientation discrimination independent of retinal matching by blowflies.

Blowflies, Phaenicia sericata, can be trained to discriminate in a learning paradigm in which one of the two visual cues is positively rewarded. Retinotopic matching of a learned visual image to the same retinal location from viewing to viewing has been hypothesized to underlie visual pattern learning and memory in insects. To address the theory of retinotopic matching, a detailed analysis was made of the flies' body orientations during learned discriminations between +45 degrees and -45 degrees gratings. Initial approaches to the positive rewarded visual cue did not originate from the same spatial location within the behavioral arena with respect to the visual cues; thus, individual flies approached the positive cue from a different vantage point from trial to trial. During initial approaches to the rewarded visual cue, the distributions of body angles with respect to the cue were different from trial to trial for each individual. These data suggest that Phaenicia sericata can learn a visual pattern with one eye region and later recognize the same pattern with another eye region. Thus, retinotopic matching is not necessary for the recognition of pattern orientation in the experimental paradigm used here. The average amount of head turning in the yaw plane was too small to compensate for the changes in body orientation exhibited by the flies. Flies view the visual patterns with distinct retinal regions from trial to trial during orientation discrimination.

Efferent neurons and specialization of abdominal segments in grasshoppers.

A specialized behavior, oviposition, is produced by the eighth and ninth abdominal segments of female grasshoppers. To begin to understand how these segments produce the behavior, which is not displayed by males or pregenital regions of the abdomen in females, the structure and function of efferent neurons in abdominal ganglia of both sexes were examined. In females, the eighth and ninth segments are specialized differently for oviposition: 20 ovipositor motor neurons were found in the eighth segment, and 26 were found in the ninth segment. Males had fewer motor neurons in their eighth segment, but the same number in the ninth segment, which is the only genital segment in males. However, the axons of several of the ninth segmental male motor neurons traveled to the periphery in the genital nerve, which is only found in males. In both sexes, pregenital ganglia had the most motor neurons, but these neurons, for the most part, had morphologies that strongly resembled those of genital segments. Efferent modulatory neuron numbers were not sexually dimorphic in the segments examined, except that males had a greater number in their ninth segment. Experimental methods that activate oviposition were found to also activate a rhythmical motor pattern in pregenital abdominal segments of both sexes. In females, the pattern was phase-coupled to oviposition, but persisted after the connections with the terminal abdominal ganglion were severed. The preponderance of similarities among efferent neurons and elicited motor activity suggests a common pattern of neural circuitry in the behaviorally diverse abdominal segments of grasshoppers.

Neurons of the median neuroblast lineage of the grasshopper: a population study of the efferent DUM neurons.

A group of lineally related neurons in the grasshopper was studied to determine the number of efferent neurons in the group and their morphological types. The neurons arise from the median neuroblast of the third thoracic neuromere and comprise what is commonly known as the DUM or dorsal unpaired median group. Of some 92 neurons in the group, about 20 are efferent neurons, the remainder being local or intersegmental interneurons. As part of our continuing developmental studies, we wished to identify the efferent neurons within the lineage and to determine their number. Ten efferent DUM neurons had been described in earlier studies, where neurons were stained individually through microelectrodes. The remaining unidentified neurons might be novel types, multiples of known types, or both, possibilities that would not be readily distinguished through further staining of neurons individually. Rather, we used methods of retrograde staining and axon tracing that allowed us to examine the entire group of efferent DUM neurons. Nineteen efferent neurons were identified, comprising two DUM1s, five DUM3s, six DUM3,4s, three DUM3,4,5s, and three DUM5s; neurons were named according to the lateral nerves containing their axons. The efferent neurons were further divided by type according to the distribution of axonal branches in lateral nerves, the course of the primary neurite within the deep or superficial DUM tract, and the diameter of the cell body.

An elliptical incised wound of the breast misinterpreted as a bite injury.

Bite injuries upon homicide victims are most often initially identified by the forensic pathologist during the course of the autopsy examination. Following such recognition, the injury or photographs of the traumatized site are then referred to a forensic odontologist for his or her examination, further characterization, and subsequent comparison with any suspect's dentition. However, if the pathologist misidentifies an injury caused by another mechanism as a human bite, this mistake can potentially be perpetuated by the dental consultant, since relatively few dentists regularly examine traumatic injuries other than those arising from bites. To illustrate such an event, a case is presented involving an incised wound of the breast, which was originally identified as an avulsive bite wound. Detailed examination by two odontologic consultants confirmed the wound as having been caused by human teeth, and further, they related the "bite injury" to a specific individual. The bite injury interpretation represented the only scientific evidence implicating the suspect at a subsequent trial for capital murder. Later examination of the tissues and photographs by a forensic pathologist and another dental consultant revealed that the injury was not due to human dentition, but rather resulted from a sharp-edged instrument. These consultants conducted a unique experiment to reduplicate the injury and prove its causation. This information was presented to the jury during the suspect's trial and resulted in his acquittal on all charges.

Thickness of facial tissues in American blacks.

The production of a three-dimensional plastic face on a human skull has been practiced sporadically since the latter part of the last century. In recent years, the technique has been revived and applied to forensic science cases. Contemporary facial reproduction are based on a small sample collected before the turn of the century. In this paper, we present data on a heretofore unstudied segment of Homo sapiens, the American black. Facial tissue thicknesses for this group vary greatly from those previously reported in European whites and in Japanese. Use of these data should make possible more accurate facial reproduction on the skulls of American blacks.