The sacral arcuate lines in upper sacral fractures

The anteroposterior radiographs of 50 patients with multiple fractures of the pelvic ring were analyzed and the findings compared with the interpretation made at the time of admission. Thirty-six of the 50 patients (72%) had associated sacral fractures. Sixty-one percent of the sacral fractures had been missed on the initial examination. Disruption, displacement, deformity, and density changes of the sacral arcuate lines are described as signs of sacral fracture.

Organization and development of brain stem auditory nuclei in the chick: ontogeny of postsynaptic responses

The onset of responsiveness to eighth nerve stimulation was examined in n. magnocellularis and n. laminaris, (second- and third-order neurons) of the chick brainstem auditory system. Extracellular microelectrode mapping techniques were used to examine postsynaptic responses in in vitro brainstem preparations. Two specific questions were addressed. First, what is the earliest time at which postsynaptic action potentials can be evoked in n. magnocellularis and n. laminaris by eighth nerve stimulation? Second, does responsiveness to eighth nerve stimulation develop along a spatial gradient in n. magnocellularis and, if so, how does this gradient compare with other developmental events observed in the chick auditory system? Postsynaptic responses in n. magnocellularis were first recorded at 11 days of incubation. Nucleus laminaris responses to direct stimulation of n. magnocellularis were also first recorded at 11 days, although n. laminaris responses to eight nerve stimulation were not seen until 12 days of incubation. A gradient of response development within n. magnocellularis was indicated by mapping of responsive sites on days 11-13. At 11 days, responses to eighth nerve stimulation were restricted to the most anteromedial portion of n. magnocellularis. Between 11 and 13 days, cells in increasingly more posterolateral portions of n. magnocellularis became responsive. This anteromedial-to-posterolateral gradient in n. magnocellularis is correlated with the basal-to-apical gradient of morphogenesis observed in the basilar papilla and morphogenetic gradients previously observed in n. magnocellularis and n. laminaris.

Synaptic excitation of the second and third order auditory neurons in the avian brain stem

Synaptic potentials were examined in the second- and third-order auditory neurons of nucleus magnocellularis and nucleus laminaris in the chick. Brain stems of mature chick embryos were explanted and maintained in vitro for 4 to 8 h. Field potentials, extracellular spike potentials and intracellular potentials evoked by 8th-nerve stimulation were examined. Eighth-nerve stimulation reliability elicited four identifiable field potentials which could be attributed to: (i) the afferent volley of the 8th-nerve axons, (ii) postsynaptic responses of n. magnocellularis neurons, and (iii) ipsilaterally and, (iv) contralaterally-evoked n. laminaris postsynaptic responses. Intracellular-recorded postsynaptic potentials were characterized by a rapid rise time and short duration. They were apparently monosynaptic with a synaptic delay of 0.4 ms. In each n. magnocellularis neuron the 'fast' excitatory postsynaptic potentials were composed of 1 to 3 all-or-none components. 'Slow' excitatory postsynaptic potentials were characterized by a longer latency, a longer duration and graded amplitude variation in proportion to the intensity of 8th-nerve stimulation. Both 'fast' and 'slow' excitatory postsynaptic potentials had similar reversal potentials. Since the 8th nerve makes monosynaptic connection with n. magnocellularis neurons, it is likely that at this synapse the 'fast' excitatory postsynaptic potentials were produced, while the 'slow' potential may be attributable to the convergence of many boutonal synapses of unknown origin. Intracellular injections of horseradish peroxidase into n. magnocellularis revealed that its efferents bifurcate below the nucleus and send one axon to the contralateral n. laminaris while the other axon forms a highly divergent projection to the ipsilateral laminar nucleus. The intracellular records obtained from n. laminaris are consistent with this anatomical finding in that graded excitatory postsynaptic potentials were elicited by 8th-nerve stimulation.

Cell interactions influencing murine marrow megakaryocytes: nature of the potentiator cell in bone marrow

Auxiliary bone marrow cells are required for optimal murine megakaryocyte colony formation in addition to progenitor cells and a colony stimulating activity (CSA) present in WEHI-3 cell conditioned medium. These auxiliary cells are adherent, with a sedimentation rate of 5.8 mm hr-1 and buoyant density of 1.065-1.078 gcm-3. The activity from bone marrow cells is loss at irradiation doses above 900 rad. Bone marrow cells with these characteristics, and supernatants from lung, bone shafts, and peritoneal exudate cells were all active in enhancing megakaryocyte colony incidences in mouse bone marrow cultures above those stimulated by an obligatory activity in WEHI-3 cell conditioned medium. Certain macrophage cell lines (J774, P388D1) could elaborate the activity. This study confirms that a potentiation activity enhances CSA stimulation of megakaryocyte colony formation. The potentiator is elaborated by bone marrow cells in limiting amounts requiring either high cell concentrations or an exogenous source of the activity for optimal colony growth.

Antifertility and toxicological studies with aromatic esters of alpha-chlorohydrin in male rats

Due to the drawbacks in the potential use of alpha-chlorohydrin itself as a male oral contraceptive, two novel crystalline derivatives, alpha-chlorohydrin-bis-m-nitrobenzoate and alpha-chlorohyrdin-mono-p-acetamidobenzoate, were synthesized and tested for antifertility activity in male rats. In addition, the nephrotoxic effects of alpha-chlorohydrin itself and of the two aromatic esters were investigated by the use of diuretic experiments, plasma biochemical analyses and kidney histology. Both esters were found to be of comparable molar potency to alpha-chlorohydrin in inducing temporary infertility following daily oral administration. The nephrotoxic effects following high oral doses of alpha-chlorohydrin were largely eliminated by the use of either ester. These derivatives have several advantages over alpha-chlorohydrin, being crystalline compounds of definable purity. Although potency was retained, acute oral toxicity was greatly reduced, due to a combination of factors - the esters were poorly absorbed in high dosage whilst relatively slow breakdown permitted effective levels to be attained on epididymal spermatozoa.

Limitation of macrophage production in long-term marrow cultures containing prostaglandin E

Addition of prostaglandin E2 (PGE2) significantly altered the cellular composition of murine long-term bone marrow cultures. After 4--5 weeks of culture, increased cellularity in the suspension phase was observed in all cultures containing prostaglandin. These suspension cells contained markedly higher proportions of differentiated neutrophils than did cells cultured in the absence of PGE2. Granulocyte-macrophage progenitor cell levels in the suspension layer were increased 3--20 fold after five weeks in prostaglandin-containing cultures compared with control cultures. Fewer cells comprised the adherent layer in cultures containing prostaglandin. The number of macrophages in this layer was reduced 3--8 fold in these cultures compared with control cultures, while the number of granulocytes was increased 2--3 fold. The progenitor cells biased toward macrophage development were selectively inhibited in the cultures with PGE2. There was no significant effect of PGE2 on pluripotent stem cell levels or on the longevity of the cultures. It is concluded that excessive monopoiesis in bone marrow may be limited by PGE2 without influencing either stem cell maintenance or the development of other marrow-derived cell types.

Isolation of pluripotent hemopoietic stem cells and clonable precursor cells of erythrocytes, granulocytes, macrophages and megakaryocytes from mouse bone marrow

Murine pluripotent hematopoietic stem cells and precursor cells with restricted commitment to erythrocytes, granulocytes and macrophages as well as megakaryocytes have been purified 30- to 50-fold from mouse bone marrow cells. Purification was achieved by a three-step procedure. Bone marrow cell populations free of erythroid cells and lymphocytes were obtained by culturing the cells for several weeks. Macrophages and adherent polymorphic neutrophils (PMN) were removed by adherence to plastic. The remainder of the PMN along with more primitive granulocytes (but not promyelocytes and some monocytoid cells) were removed either by neutral density centrifugation or by differential centrifugation after rosette formation with sheep erythrocytes coated with immunoglobulin (EA rosettes). The remaining population of marrow-derived cells contained 40-66% blast cells, 20-35% promyelocytes and 5-10% other cells (usually PMNs and monocytes). Using cloning techniques to detect immature hemopoietic cells, this population contained 15-35% granulocyte-macrophage progenitor cells, approximately 0.2% erythroid burst-forming cells, approximately 0.1% megakaryocyte progenitor cells and 1-3% pluripotent stem cells (based on seeding efficiency 0.06).

Pleomorphism in Cellulomonas acidula

Pleomorphism of Cellulomonas acidula in liquid and on solid media is described. Growth in liquid medium is characterized initially by the formation of club-shaped rods and later by cocci. On solid media the organism formed irregular branched cells and large swollen cells.

Effect of racemic and S(+) alpha-chlorohydrin-1-phosphate on glyceraldehyde-3-phosphate dehydrogenase in relation to its contraceptive action

The phosphate esters of racemic (+/-) alpha-chlorohydrin and its S(+)-optical isomer have been prepared as cyclohexylamine salts. In vitro both inhibited glyceraldehyde-3-phosphate dehydrogenase by a competitive mechanism, whereas (+/-) alpha-chlorohydrin did not. The S(+)-isomer was approximately four times as potent as the racemate. These results correlate with data concerning the relative contraceptive activity in rats of racemic and S(+) alpha-chlorohydrin. They support the view that the antifertility mechanism involves in vivo formation of S(+) alpha-chlorohydrin-1-phosphate, with resulting inhibition of glycolysis in sperm.

Ontogeny of behavioral responsiveness to sound in the chick embryo as indicated by electrical recordings of motility

The primary purpose of these experiments was to gather normative behavioral data regarding the ontogeny of responsiveness to sound in the chicken embryo. As a prerequisite, a sensitive ane accurate method for recording embryonic motility was developed (Experiment 1). By means of platinum electrodes inserted just beneath the shell membrane, potentials resulting from heartbeat and movement were recorded on a polygraph. The technique was found to be effective when applied to chick embryos 6 days and older. Correlations between visual observations of activity and the records produced by the electronic technique substantiated its accuracy. Behavioral responses of chick embryos (Stages 39-43) to acoustic stimulation (Experiment 2) were then recorded. High-intensity (115-dB SPL) tones of 400, 700, and 1400 Hz were used as stimuli. The earliest consistent responses were recorded from Stage 40 (ca. Days 14-15) subjects; the 700 and 1400 Hz tones produced statistically reliable inhibition of movement during the stimulus period compared with the post-stimulus period. Reliable increases in movement during the stimulus period were first recorded at Stage 42 (ca. Days 16-17) in response to 700 and 1400 Hz and at Stage 43 (ca. Days 17-18) in response to 400 Hz.

Regulation of proliferation of murine megakaryocyte progenitor cells by cell cycle

The extent to which mouse megakaryocyte progenitor cells (colony-forming unit-megakaryocyte, CFU-M) can proliferate in semisolid cultures prior to endomitosis, and conditions that may regulate that differentiation step, were investigated. The proliferative capacity of CFU-M was determined by estimating the number of megakaryocytes per colony. A bimodal distribution was observed (modal values, 10-15 and 25-30 cells/colony), indicating that separate megakaryocyte progenitor cells may be biased in their capacity for proliferation versus endomitosis. Differences were observed in the cell cycle characteristics of CFU-M as determined in vivo and in vitro that suggest that maturation of CFU-M into megakaryocytes may be regulated within the marrow by control of the cell cycle of the megakaryocyte precursor cell.