Nuclear magnetic resonance evaluation of synovial fluid and articular tissues

In vitro studies were performed on joint tissues and fluid to evaluate the potential for nuclear magnetic resonance (NMR) in the study of joint disease. Values for spin lattice relaxation times, spin-spin relaxation times and mobile proton content were obtained on 51 consecutive whole synovial fluids (SF). Correlations were sought between NMR values and white blood counts, protein content, calcium, phosphorus, and diagnosis. Only a very weak correlation (0.444) was noted with total SF protein. Albumin added in vitro did produce good correlation (0.975). NMR values were not altered by the addition of monosodium urate, of calcium pyrophosphate, or hydroxyapatite crystals. In vitro measurements of dissected canine articular tissue showed differences in NMR between the different joint components and between inflamed and noninflamed tissues. Our findings suggest that estimation of the amount of inflammation by NMR values is not possible at this time, but with refinements of techniques, magnetic resonance imaging may provide superb images of articular soft tissue structures.

Cyclic adenosine 3'5' monophosphate stimulates prostaglandin E production by human adherent synovial cells

Production of prostaglandin E (PGE) by rheumatoid synovium appears important to regulation of the pathologic process in rheumatoid arthritis. Cells derived from human synovium by proteolytic digestion produce large amounts of PGE which in turn can elevate synovial cell cAMP levels and inhibit cell proliferation. Data presented here indicate that cAMP can further increase production of PGE from adherent synovial cells (ASC). PGE production occurs over 12-72 hr and is not due to the ability of cAMP to inhibit cell proliferation. Exposure of cells to cAMP results in increased release of 3H arachidonic acid from precursors but not in activation of the cyclooxygenase enzyme. This phenomenon suggests the presence in adherent synovial cells of a mechanism for amplifying PGE production.

Inspiratory rhythm in airway smooth muscle tone

In anesthetized paralyzed open-chested cats ventilated with low tidal volumes at high frequency, we recorded phrenic nerve activity, transpulmonary pressure (TPP), and either the tension in an upper tracheal segment or the impulse activity in a pulmonary branch of the vagus nerve. The TPP and upper tracheal segment tension fluctuated with respiration, with peak pressure and tension paralleling phrenic nerve activity. Increased end-tidal CO2 or stimulation of the carotid chemoreceptors with sodium cyanide increased both TPP and tracheal segment tension during the increased activity of the phrenic nerve. Lowering end-tidal CO2 or hyperinflating the lungs to achieve neural apnea (lack of phrenic activity) caused a decrease in TPP and tracheal segment tension and abolished the inspiratory fluctuations. During neural apnea produced by lowering end-tidal CO2, lung inflation caused no further decrease in tracheal segment tension and TPP. Likewise, stimulation of the cervical sympathetics, which caused a reduction in TPP and tracheal segment tension during normal breathing, caused no further reduction in these parameters when the stimulation occurred during neural apnea. During neural apnea the tracheal segment tension and TPP were the same as those following the transection of the vagi or the administration of atropine (0.5 mg/kg). Numerous fibers in the pulmonary branch of the vagus nerve fired in synchrony with the phrenic nerve. Only these fibers had activity which paralleled changes in TPP and tracheal tension. We propose that the major excitatory input to airway smooth muscle arises from cholinergic nerves that fire during inspiration, which have preganglionic cell bodies in the ventral respiratory group in the region of the nucleus ambiguus and are driven by the same pattern generators that drive the phrenic and inspiratory intercostal motoneurons.

Effect of hyperthermia on murine myeloid precursors

Murine bone marrow was exposed to hyperthermia temperatures of 41.5 to 45.5 degrees C. The proliferation capacity of myeloid progenitor and committed precursors was assayed in vivo utilizing spleen colony formation and diffusion chamber (DC) techniques. The survival of both pluripotential (CFU-S) and committed myeloid (CFU-DG) stem cells decreased exponentially with an increase in the heating period. Progression from CFU-S to CFU-DG significantly altered thermal sensitivity in the temperature range examined. Proliferation of mature granulocyte-monocytes (G-M) in DC is more thermostable than their stem cell precursors. Heat inactivation energies (enthalpies) of CFU-S and CFU-DG were derived from the slope of the heating time survival curves. Enthalpy of CFU-S is 300 kcal/mole below 43 degrees and 105 kcal/mole above 43 degrees. The enthalpy of CFU-DG is 250 and 145 kcal/mole below and above 43 degrees, respectively.

Chloroquine inhibits the production of a mononuclear cell factor by inhibition of lectin binding

The effect of chloroquine (CQ) on the ability of normal human peripheral blood monocytes to produce a soluble mononuclear cell factor (MCF) capable of stimulating prostaglandins from adherent rheumatoid synovial cells was studied. CQ inhibited concanavalin A (Con A)- and bacterial peptidoglycan-induced MCF activity, but not colchicine-induced activity, in a dose-dependent manner. After incubation with CQ for 20 minutes, 3H Con A binding was reduced by 50%, and metabolism of pre-bound 3H Con A was inhibited. These data suggest that CQ can inhibit MCF production by inhibition of lectin binding, perhaps by inhibition of receptor recycling.

Hematopoietic regulatory factors produced in long-term murine bone marrow cultures and the effect of in vitro irradiation

The nature of hematopoietic regulatory factors elaborated by the adherent (stromal) cells of long-term murine bone marrow cultures and the effect of in vitro stromal irradiation (XRT) on the production of these factors was investigated. Using an in situ stromal assay employing a double layer of semisolid agar, it was possible to demonstrate stromal elaboration of at least two colony-stimulating activities, ie, granulocyte/macrophage colony-stimulating activity (G/M-CSA) and megakaryocyte colony-stimulating activity (Meg-CSA). Exposure of the stroma to XRT resulted in dose-dependent elevations of both activities that correlated inversely with total myeloid cell mass as determined by concurrent reductions in total supernatant cell recoveries from irradiated cultures. Mixture experiments that combined control and irradiated stroma revealed that the hematopoietically active control stroma could block detection of XRT-related G/M-CSA elevations. These data implicate a local negative feedback mechanism in the regulation of hematopoiesis. Antiserum directed against purified L cell colony-stimulating factor (CSF) reduced granulocyte/macrophage colony formation in the target layer but did not effect the increased Meg-CSA. While a radioimmunoassay for L-cell type CSF was unable to detect significant differences in concentrated media from control and irradiated cultures, bioassays of these media revealed XRT-related G/M-CSA elevations. These results indicate that the G/M-CSA elaborated in these cultures is immunologically distinct from the Meg-CSA produced, and although distinct from L cell CSF, the G/M-CSA is crossreactive with the L cell CSF antiserum. Morphologic, histochemical, and factor VII antigen immunofluorescent studies were performed on the stromal cell population responsible for production of these stimulatory activities. In addition to "fat" cells, the stromal cells remaining after XRT were composed of two predominant cell populations. These included a major population of acid phosphatase and nonspecific esterase-positive macrophage-like cells and a minor population of factor VII antigen negative epithelioid cells.

The response of previously irradiated skin to combinations of fractionated X radiation, hyperthermia, and cis-diamminedichloroplatinum

Mouse legs were irradiated with a dose of 30 Gy. After 50 days, when the acute reaction had regressed to a steady state, they were retreated with either 30 Gy of X rays delivered in six fractions over 12 days, six exposures to hyperthermia for 45 min at 42.7 degrees C, six doses of cis-DDP, or a combination of these agents. The maximum skin reactions and the skin reactions integrated over 50 days were determined. The maximum skin response was found when the previously irradiated skin was treated with a combination of X irradiation and hyperthermia. The addition of cis-DDP to this regimen did not result in a further enhancement of the skin reaction. When the second treatment was irradiation alone or cis-DDP alone, the severity of the skin reactions was similar. Injury from the initial radiation dose persisted so that the cytotoxic action of cis-DDP resulted in a level of subacute skin damage that was similar to a second course of X irradiation.

Influence of ultrasound-induced hyperthermia and X-irradiation on the incidence of metastases from a solid tumor

The KHT sarcoma transplanted into mouse legs was treated by X-irradiation, hyperthermia or a combination of X-irradiation plus hyperthermia. Neither 20 Gy of X-irradiation or hyperthermia for 60 min were effective in controlling the local tumors when used alone. Simultaneous treatments, however, resulted in 22% of the tumors being locally controlled corresponding to a TER of 2.0. Local control was increased when irradiation was given 1 h before or after hyperthermia, TER 2.8 and was maximum, TER 2.9, when the hyperthermia was 0.1 h after irradiation. When the local tumor was controlled by irradiation alone or by irradiation delivered 1 h before or after hyperthermia, all of the metastases that subsequently occurred arose before or during treatment. When tumors were locally controlled by radiation given during or immediately after hyperthermia, metastases developed that must have occurred as a consequence of the treatment. The treatment sequence that resulted in a maximum TER for tumor control did not correlate with the risk of metastatic spread. The timing of the irradiation in relation to hyperthermia may explain some contradictory findings regarding the influence of heat on the incidence of metastases. Hyperthermia did not affect the distribution of anatomic sites involved with metastases or the ratio of lymphatic to hematogenously spread metastases.

Lithium stimulation of murine hematopoiesis in liquid culture: an effect mediated by marrow stromal cells

Lithium has previously been observed to stimulate in vitro Dexter culture hemopoiesis with increases in granulocytes, megakaryocytes, and pluripotent stem cells (CFU-S). In the present study, a two-phase murine Dexter culture system was established to study the mechanism of lithium-mediated stem cell stimulation. Different lots of horse sera or fetal calf sera were found to have markedly different effects on Dexter culture growth; given the appropriate sera supplementation, supernatant cells from Dexter cultures established from C57BL/6J mice 3 wk previously were free of stromal-forming capacity, but had stem cells and could grow on 900-950 R irradiated stroma. Conversely, in vitro irradiation (900-950 R) of 3-wk cultures resulted in a stem-cell-free adherent monolayer that could support growth for up to 9 wk in culture. The stroma from Dexter cultures preexposed to lithium chloride (1.0 mmole/liter) for 3 wk, irradiated (900 R), and then refed with 3-wk Dexter supernatant cells has an enhanced capacity to support cell production, CFU-S, and probably granulocyte-macrophage colony-forming cell (GM-CFU-C) production, as compared to stroma not preexposed to lithium. Lithium carryover was ruled out in these experiments. These data indicate that lithium stimulates CFU-S and in vitro granulopoiesis by an indirect effect on a radioresistant adherent stromal cell.

The response of previously irradiated skin to combinations of X radiation and ultrasound-induced hyperthermia

Areas of skin approximately 1.5 cm in diameter on the legs of mice were made hyperthermic (30 min at 42.7 degrees C) by exposure to an ultrasound beam (780 kHz), a single dose of X irradiation (2000 rad), or a combination of these treatments. After 35 days, when the acute reaction had reached a steady state, the same tissue was given a second treatment by either hyperthermia, irradiation, or a combination of hyperthermia and irradiation. When the first treatment was irradiation and the second treatment was either irradiation or a combination of hyperthermia and irradiation, the acute skin reactions were similar to those of skin not previously irradiated, indicating a large proportion of recovery from the first irradiation. When irradiation was the first treatment, a comparison of second treatments by hyperthermia plus irradiation with irradiation alone showed a thermal enhancement of 1.45. When the first treatment was hyperthermia plus irradiation, a comparison of second treatments by hyperthermia plus irradiation with irradiation also showed an enhancement factor of 1.45 for the combined treatment.

Transmission in airway ganglia of ferrets: inhibition by norepinephrine

We examined the possibility that norepinephrine inhibits transmission in parasympathetic ganglia of the ferret trachea. We impaled ganglion cells on recording microelectrodes and evoked postsynaptic action potentials by stimulating fiber tracts entering the ganglion. When norepinephrine was added to the recording bath, the action potentials were blocked. Phentolamine reversed this block. These results indicate that, by activating alpha-receptors, norepinephrine inhibits transmission in airway ganglia.

The role of polyamine biosynthesis in hematopoietic precursor cell proliferation in mice

Under the influence of a selective irreversible inhibitor of ornithine decarboxylase (ODC), DL-alpha-difluoromethylornithine (DFMO), early hematopoiesis was enhanced. In the bone marrow, the absolute number of cells that give rise to spleen colonies in lethally irradiated mice (CFU-S), granulocytic colonies in diffusion chambers in mice (CFU-DG), and granulocyte-monocyte colonies in agar in vitro (CFU-C) was increased 2-4 fold. This could be abrogated by administration of putrescine, confirming the association of the stimulatory effect with polyamine biosynthesis most likely via depression of ornithine decarboxylase activity and subsequent synthesis of putrescine. Analysis of cell cycle characteristics by 3H-TdR suicide technique demonstrated that the proportion of CFU-S, CFU-DG, and CFU-C in S-phase was significantly increased. Additionally, the stimulatory effect was reflected by enhanced colony formation in diffusion chambers implanted intraperitoneally in mice receiving DFMO. This could also be eliminated by treatment of the host animal with putrescine, again suggesting that polyamine biosynthesis plays an important role at the early stages of hematopoiesis in vivo. Effect of DFMO on colony formation in vitro (CFU-C) was inhibitory and not reversible with putrescine. It could be partially eliminated by aminoguanidine, which neutralizes diamine oxidase present in fetal calf serum used in the CFU-C assay. These data suggest that the effect of DFMO in vitro was nonspecific.

Rheumatoid synovial cell morphologic changes induced by a mononuclear cell factor in culture

Adherent rheumatoid synovial cells in culture produce large amounts of prostaglandin E2 (PGE2) and collagenase. When exposed to a monocyte-derived factor, such cells exhibit marked increases in PGE2 and collagenase production. In addition, cellular morphology becomes more stellate. In the presence of this factor, indomethacin inhibits both PGE2 production and the stellate changes, whereas collagenase production usually continues at a high rate. Addition of PGE2 to cultures reproduces the stellate change as does the cyclic adenosine monophosphate (cAMP) analog 8-bromo-cAMP. Colchicine inhibits morphologic transformation induced by the monocyte-derived factor, whereas cytochalasin B has no effect. It appears that the stellate morphology is dependent upon PGE2-induced cAMP stimulation and is not related to collagenase production per se.

The response of kidney to ionizing radiation combined with hyperthermia induced by ultrasound

Mouse kidneys were made hyperthermic (42.5 degrees C for 30 min) one hour before, during, or one hour after local irradiation to determine the effect of hyperthermia on radiation damage. An ultrasound beam was used to induce hyperthermia. The urinary concentrations of total protein and albumin were used as criteria of kidney injury. Hyperthermia alone did not induce proteinuria. Radiation alone produced proteinuria that was not correlated with dose. Hyperthermia induced during or after irradiation resulted in a thermal enhancement factor of 1.29 +/- .33. Hyperthermia induced one hour before irradiation resulted in a thermal enhancement factor of 0.88 +/- .05, indicating a radioprotective effect. To the authors' knowledge, this is the first time such an effect has been shown.

Tracheal contraction and relaxation initiated by lung and somatic afferents in dogs

Capsaicin injected into the right heart of dogs causes reflex bronchoconstriction by stimulating pulmonary C-fibers, but injected into the left heart it is said to have little effect even though it stimulates bronchial C-fibers, which are known to cause contraction of airway smooth muscle. Attempting to resolve this apparent contradiction, we recorded smooth muscle tension in an innervated tracheal segment in anesthetized dogs and examined the reflex effects of injecting capsaicin intravascularly at different sites. Right atrial injection of capsaicin (10 micrograms/kg) caused tracheal contraction, as did bronchial arterial injection (0.15-5.0 micrograms); left atrial injection (10 micrograms/kg), however, caused relaxation or slight contraction, or a combination of the two. Contraction but not relaxation was abolished by cutting or cooling (0 degree C) the cervical vagus nerves. Femoral arterial injection (10-100 micrograms) caused tracheal relaxation, which was abolished by cutting hindlimb nerves. We conclude that both pulmonary and bronchial C-fibers evoke tracheal contraction, but when capsaicin is injected into the left atrium any effects of stimulating bronchial C-fibers are masked by the reflex action of somatic afferents, which cause tracheal relaxation.

The radiobiological basis for tissue reactions in the oral cavity following therapeutic x-irradiation. A review

The radiobiological basis for the response of tissues in the oral cavity following therapeutic doses of ionizing radiation has been reviewed. Clinical manifestations of radiation response occur when the functional compartment of the tissue, the parenchymal cells, is depleted to some minimal value. The time course and severity of the response depend on the sensitivity of cellular compartments, the vegetative intermitotic compartment being the most sensitive and the fixed postmitotic cells being the least sensitive. Early responses are therefore seen in rapid cell renewal systems while the chronic effects are closely correlated with damage to the terminal vascular bed, a multipotential connective tissue compartment. Osteonecrosis of bone following irradiation involves a series of events, including a decreased salivary gland function, devitalization of bone, and infection. Carcinogenesis in oral cavity tissues is a very rare late sequela of therapeutic radiation.

Local thermodilution: a reliable technique for estimating renal blood flow in the rabbit

1. A thermistor probe designed for determination of renal blood flow in rabbits, consisted of a fast-responding bead thermistor and an injection port which was also used to measure renal venous pressure between injections. 2. By an in vitro calibration system, actual measured flow (Qa) correlates well with the thermodilution calculated flow (Qc), where Qc = 0.99 Qa + 4.9 (r = 0.97, n = 42). 3. The renal blood flow (RBF) as determined by the thermodilution technique in 3 control groups was 53 +/- 3 (8), 60 +/- 6 (8), and 62 +/- 3 (3) ml/min/kidney or about 9% of the cardiac output. 4. Hypovolemia (-10%) reduced RBF by 19% from the control value, whereas, hypervolemia (+10%) did not alter RBF. 5. Smoke-induced apnea resulted in hypertension (+30%) and bradycardia (-39%), and was associated with changes in RBF (-55%) and renal vascular resistance (+183%). 6. We conclude that the local thermodilution technique is a relatively easy and reliable method for estimating RBF in rabbits.

Effect of ultrasound-induced hyperthermia and cis-diamminedichloride platinum II on murine renal function

Murine renal function was evaluated after ultrasound-induced kidney hyperthermia (42.5 degrees C and 46.5 degrees C for 35 minutes) and the administration of cis-diamminedichloride platinum II (8 mg/kg). A quantitative immunonephelometric technique was employed to determine urinary total protein (TP) and albumin (Alb) 1-180 days post-treatment. Hyperthermia of 46.5 degrees C elevated urinary TP excretion significantly more than that of 42.5 degrees C cis-diamminedichloride platinum (Cis DDP) administration greatly increase urine TP with a peak mean TP concentration of 488 microgram/ml, four days after Cis DDP (normal range was 26-48 microgram/ml). This returned to normal by day 14. The TP excretion after 42.5 degrees C hyperthermia with concurrent Cis DDP was similar to Cis DDP alone, implying there was no potentiation of early or late Cis-DDP-induced renal damage by hyperthermia. Late mouse mortality was greater (P = 0.08) after Cis DDP alone, than Cis DDP with 42.5 degrees C hyperthermia. There was a statistically significant increase (P less than 0.05) in the Alb/TP excretion ratio after the addition of 42.5 degrees C hyperthermia to Cis DDP, implying an alteration in the site or nature of the Cis DDP renal lesion by hyperthermia.

Reflex tracheal contraction induced by stimulation of bronchial C-fibers in dogs

Bradykinin stimulates the afferent vagal endings of bronchial C-fibers but has little effect on other pulmonary vagal afferents. In anesthetized dogs with open chest, we recorded transverse tension in the posterior wall (trachealis muscle) of an upper cervical tracheal segment and stimulated bronchial C-fibers selectively by injecting bradykinin (19 ng-3 microgram) into a bronchial artery. The recurrent and pararecurrent laryngeal nerves were cut so that the superior laryngeal nerves provided the motor supply to the segment. Bradykinin caused a dose-dependent increase in tracheal muscle tension and often a conspicuous decrease in heart rate, which were abolished by vagotomy or administration of atropine. Injection of bradykinin still evoked tracheal contraction when myelinated lung afferents were blocked by cooling the midcervical vagi to 7 degrees C, but contraction was abolished when unmyelinated lung afferents were blocked by cooling to 0-1 degrees C, the effects of cooling being reversible. Our results indicate that stimulation of bronchial C-fibers, like that of pulmonary C-fibers, evokes reflux contraction of airway smooth muscle and reflex cardiac slowing.

Temperature-dependent inhibition of murine granulocyte-monocyte precursors

The response of nucleated bone marrow cells from C3H mice to hyperthermic temperatures of 41.5 to 49.5 degrees for a fixed heating period of 30 min has been determined. The threshold temperatures for cell lysis, loss of trypan blue exclusion, and histological evidence of cell injury were greater than 49.5 degrees, 45.5 degrees and 43.5 degrees, respectively. Growth of mature granulocyte-monocytes from precursors was evaluated in Millipore diffusion chamber culture. There was a biphasic decrease in granulocyte-monocyte growth after exposure to temperatures of 41.5 to 45.5 degrees. The ratio of granulocytes to monocytes in proliferated cultures was not altered after hyperthermia. Pluripotent and committed granuloid stem cells were assayed by the spleen colony and plasma clot diffusion chamber techniques. These also showed a biphasic decrease with increase in temperature, with committed stem cells having a greater thermal sensitivity at lower temperatures.

Medical radiation exposure and genetic risks

Everyone is exposed to background radiation throughout life (100 mrem/year to the gonads or 4 to 5 rem during the reproductive years). A lumbosacral series might deliver 2,500 mrem to the male or 400 mrem to the female gonads. A radiologic procedure is a cost/benefit decision, and genetic risk is a part of the cost. Although cost is usually very low compared to benefit, if the procedure is unnecessary then the cost may be unacceptable. On the basis of current estimates, the doubling dose is assumed to be 40 rem (range 20 to 200) for an acute dose, and 100 rem for protracted exposure. Although there is no satisfactory way to predict the size of the risk for an individual exposed, any risk should be incentive to avoid unnecessary radiation to the gonads. Conception should be delayed for at least ten months for women and three or four months for men after irradiation of the gonads. The current incidence of genetically related diseases in the United States population is 60,000 per million live births. Based on the most conservative set of assumptions, an average gonadal dose of 1,000 mrem to the whole population would increase the incidence of genetically related diseases by 0.2%.

Search for a cardiac nociceptor: stimulation by bradykinin of sympathetic afferent nerve endings in the heart of the cat

1. We have examined the effect of bradykinin on impulse traffic in sympathetic afferent fibres from the heart, great vessels and pleura, and have attempted to identify cardiac nociceptors that on the basis of their functional characteristics might have a role in the initiation of cardiac pain. 2. In anaesthetized cats, we recorded afferent impulses from 'single-fibre' slips of the left 2nd--5th thoracic rami communicantes and associated chain, and selected fibres arising from endings in the heart, great vessels, pericardium and pleura. We applied bradykinin solution (0 . 1--1 . 0 microgram/ml.) locally to the site of the ending; we also injected bradykinin (0 . 3--1 . 0 microgram/kg) into the left atrium. 3. Afferent endings excited by bradykinin (159 of 191 tested) were of two types. The larger group (140) were primarily mechanoreceptors with A delta of C fibres (mean conduction velocity, 7 . 5 +/- 0 . 6 m/sec). They were very sensitive to light touch. Those located in the heart, great vessels or overlying pleura had a cardiac rhythm of discharge and were stimulated by an increase in blood pressure or cardiac volume. 4. Bradykinin increased mechanoreceptor firing from 0 . 7 +/- to 5 . 0 +/- 0 . 3 (mean +/- S.E. of mean) impulses/sec. Some endings appeared to be stimulated directly by bradykinin, others sensitized by it so that they responded more vigorously to the pulsatile mechanical stimulation associated with the cardiac cycle. 5. The smaller group of eighteen endings, of which ten were in the left ventricle, were primarily chemosensitive. Most had C fibres, a few had A delta fibres (mean conduction velocity, 2 . 3 +/- 0 . 7 m/sec). They were insensitive to light touch. With one exception they never fired with a cardiac rhythm, and even large increases in aortic or left ventricular pressure had little effect on impulse frequency. 6. Chemosensitive endings were stimulated by bradykinin, impulse activity increasing from 0 . 6 to 15 . 6 +/- 1 . 3 impulses/sec and remaining above the control level for 1-3 min. The evoked discharge, which was either continuous or occurred in irregular bursts, was not secondary to mechanical changes in the heart and great vessels. 7. Tachyphylaxis occurred when the interval between successive applications of bradykinin was 20 min or less. It was a feature of the response of both mechanosensitive and chemosensitive endings. 8. Because of their responsiveness to changes in pressure and their sensitivity to light touch, the mechanosensitive endings appear to be unlikely to subserve a primarily nociceptive function, although they may be responsible for evoking some of the components of the pseudoaffective response. By contrast, the chemosensitive endings appear well fitted to act as cardiac nociceptors.

Carotid sinus nerve efferents: properties and physiological significance

The significance of a sympathetic efferent nerve supply, vasoconstrictor to the carotid body and hence facilitatory to carotid chemoreceptors, is well understood. The significance of a second efferent pathway, whose impulses, passing down the sinus nerve, are inhibitory to the chemoreceptors, is less certain. Activity in these sinus nerve efferents is increased by injection of pressor agents, by hypoxia, by hypercapnia, by application of alkaline solutions to the ventral medulla, and by severe hypocapnia. All these stimuli appear to act centrally. Sinus nerve efferents can also be activated reflexly by stimulating ipsilateral carotid chemoreceptors. The mechanism of efferent inhibition is disputed. A purely cholinergic vasodilator role is unlikely because inhibitory effects are abolished by alpha-adrenergic antagonists. Sinus efferents probably cause release of an inhibitory transmitter, dopamine, but convincing evidence for a releasing mechanism has yet to be obtained. Stimulation of nociceptive endings in the heart has reciprocal effects on sinus nerve efferents and sympathetic efferents to the carotid body, inhibiting the former and stimulating the latter. Recent results are cited which indicate that the responses of sinus nerve efferents to changes in blood pressure are more variable than is generally believed, and that the conventional explanation of the relationship between sinus efferent activity and arterial pressure needs to be revised.

Bradykinin stimulates afferent vagal C-fibers in intrapulmonary airways of dogs

Bradykinin is released in the lungs in asthma and pulmonary anaphylaxis. It has negligible direct bronchoconstrictor effects in humans or dogs, but inhaled as aerosol it causes cough and reflex bronchoconstriction in asthmatics and some normal subjects. The afferent nerves responsible for these reflex effects have not been identified. We recorded vagal impulses in anesthetized dogs to determine whether lung afferents were stimulated by bradykinin. C-fiber endings in the intrapulmonary airways accessible from the systemic circulation were stimulated by bradykinin injected into the left atrium (0.5-1.0 micrograms/kg) or bronchial artery (1.5 micrograms), activity increasing 15-fold on average. C-fiber endings accessible from the pulmonary circulation were relatively insensitive to bradykinin. Bradykinin caused a small increase in firing of some rapidly adapting (irritant) receptors, but the effect appeared to be secondary to vascular changes. Bradykinin had variable effects on slowly adapting stretch receptors, but did not stimulate them directly. Thus vagally mediated sensory or reflex effects initiated by bradykinin in the lung are probably due to stimulation of "bronchial" C-fibers.

Response of mouse kidney to hyperthermia: pathology and temperature--dependence of injury

Hyperthermia either alone or in combination with radiotherapy and chemotherapy is being used increasingly in the treatment of malignant tumors. This study was designed to evaluate the response of the mouse kidney exposed to a range of hyperthermic temperatures (41 to 45 degrees C) used to induce regression of malignant tumors. Minimal histologic evidence of renal injury occurred in the proximal tubules of the subcapsular region. More extensive damage was characterized by necrosis of tubules and glomeruli in a sharply circumscribed area that involved the lateral subcapsular area where the temperature induced was highest. The tissue histologic reaction was maximal by 24 hours. At temperatures below 41 degrees C no necrosis occurred, whereas at temperatures between 42 and 45 degrees C there was an increasing incidence of necrosis. This increase in tissue reaction above 42 to 43 degrees C is consistent with reported observations from tissue culture and in vivo skin heating experiments, and indicates that normal tissue injury may occur in the same range of temperatures shown to cause regression in malignant tumors.

Immunonephelometric assay for urinary total protein and albumin in mice

A quantitative immunonephelometric assay for measuring total protein and albumin in mouse urine has been developed. Antisera to whole mouse sera or to mouse albumin was added to aliquots of urine and the antigen-antibody complexes formed were measured by laser nephelometry. Sample volumes were small (20 microliters) and the assay time was 90 minutes. The assays were sensitive to 10 mg/L and within-day and day-to-day precision studies demonstrated coefficients of variation of less than 15%. Average urinary total protein and albumin concentrations for random urine specimens in female C3H mice (age 80-150 days) were 42 and 24 mg/L respectively. Urinary total protein and albumin to creatinine ratios were also determined.

Factors affecting the physical performance of the rat in hyperbaric environments

Experiments were designed to partition the effect of inspired oxygen tension (PIO2), gas density (rho), and ambient pressure (P) at rest and during exercise in rats. At rest oxygen uptake (VO2) was reduced by 19.5% (P less than 0.01) in 3 ATA air and by 32.1% (P less than 0.01) in 10 ATA air from 1 ATA air control of 29.3 +/- 1.21 (SE) ml/min.kg; there was no difference in VO2 between 1, 3, and 10 ATA He mixtures containing 20% O2. During exercise, VO2 was depressed by 36.2% (P less than 0.01) in 3 ATA air from 1 ATA air value of 55.3 +/- 3.23 ml/min.kg; VO2 was unaffected in 3 ATA He containing 20% O2 as compared to that of 46.5 +/- 2.43 ml/min.kg at 1 ATA He-O2 ambient. These VO2 values were compared to that obtained from normoxic ambients for separation of effects of elevated PIO2, P, and rho on VO2 at rest and during exercise. The effect of PIO2 was deduced by comparing VO2 in normoxic and hyperoxic He and N2 at a given P and rho. The density effect was obtained by comparing the VO2 in various densities at a given P and PIO2. The P effect was obtained by comparing the VO2 in various ambient pressures at a given rho and PIO2. Summation of the effects of P, rho, and PIO2 sufficiently approximates the changes in VO2 at rest. The same procedure underestimates the actually measured VO2 in all N2 ambients.

The use of 2450 megahertz of microwave in cancer therapy; a pilot study

Contraindications to microwave diathermy traditionally include malignant tumors. This paper describes a pilot study of tissue hyperthermia treatment (average 42.5 degrees C, 108.5 degrees F) for superficial cancers, using 2450 megahertz of microwave diathermy. Tissue temperatures were recorded for prolonged periods of time, and tumor responses to heat alone, or to heat combined with radiation therapy, were observed. Such treatments were tolerated by the patients, but were not without side effects. Preliminary results of this pilot study, as well as those of other investigators, showed that tissue hyperthermia would be a useful treatment modality for cancer therapy. The familiarity of physical therapists with microwave diathermy may be an asset to them as clinicians. Physical therapists, however, should not attempt to treat cancer patients alone. Further clinical research in the area should be conducted in the proper setting under the guidance of an oncologist.

Influence of a chronic environmental stress on the incidence of methylcholanthrene-induced tumors

The influence of a chronic environmental stress, living in a 2 degrees environment, on the incidence of methylcholanthrene-induced tumors in albino female Simonsen rats, a Sprague-Dawley-derived strain, was studied. The results indicated that the metabolic rate was double for rats kept at 2 degrees, compared with those kept at 25 degrees. Exposure to 2 degrees for life, with no other treatment, reduced median life expectancy to 560 days compared with 686 days for rats kept at 25 degrees. Transfer to a 2 degrees environment after 250 days at 25 degrees reduced the incidence of spontaneous tumors, while transfer to 25 degrees after 250 days at 2 degrees increased the incidence of tumors compared to that for rats always kept at 25 degrees. Exposure to an environmental temperature of 2 degrees immediately following a carcinogenic stimulus (3-methylcholanthrene, 2 mg s.c.) significantly reduced the incidence of tumors compared to that in rats kept at 25 degrees but did not change tumor induction time. The reduced tumor incidence may have resulted from inhibition of the carcinogenic transformation by chronic stress. The survival time of rats with 3-methylcholanthrene induced tumors was not significantly less in a 2 degrees environment than it was at 25 degrees.

Effects of head-out water immersion on cardiorespiratory responses to maximal cycling exercise

Our objectives were to determine effects of head-out immersion (HOI), scuba breathing, and water temperature on cardiorespiratory responses to maximal aerobic work. Measurements of VO2, VE, and heart rate (HR) were obtained on seven men (27 yr, 177 cm, 67 kg) as they performed the same upright bicycling exercise to exhaustion (4-5 min) in 23 degrees C air and 30 degrees C water. Maximal oxygen uptake (VO2 max) during HOI was 3.18 liters - min-1, which was not statistically different from the mean of 3.29 liters- min-1 in air. When compressed air was breathed via scuba during HOI, VO2 max was 3.12 liters- min-1 and not significantly different from that when room air was breathed and a low-resistance valve in water was used. HOI decreased VE by 15.7 liters - min-1 and HR by 10 beats (b) - min-1. Scuba breathing further reduced VE by 22.0 liters - min-1. Similar measurements were made on four of the subjects after 18 min of HOI in water temperatures of 35,30, and 25 degrees C. Water temperature had no significant affect on VO2 max, although HR was 8 b- min-1 lower in 30 degrees C and 15 b - min-1 lower in 25 degrees C as compared to 35 degrees C water. The results show that VO2 max was not significantly changed by HOI, scuba breathing, or brief exposures to 25, 30, and 35 degrees C water, despite significant reductions that occurred for VE and HR.

Protection of the skin of mice against irradiation with cyclotron-accelerated helium ions by 2-mercaptoethylamine

Mouse skin was exposed to doses of 1 250 to 3 000 rad using a helium ion beam with modal LET of 15 keV per micron. The skin reactions were evaluated for mice treated with a topical application of 10% MEA in a cream base or a placebo 15 minutes before irradiation. A comparison of the skin reactions indicated that the MEA treatment resulted in a DMF of at least 1.2. The implication for radiation therapy was discussed.

The influence of thyroid stimulation on the incidence of 3-methylcholanthrene-induced tumors

The incidence of tumors induced by a single s.c. injection of 2 mg of 3-methylcholanthrene was observed in euthyroid and thyroidectomized rats and in rats fed thyroid powder. Thyroid feeding increased the metabolic rate by a factor of 1.6 and reduced the incidence of tumors at the site of injection from 92% in euthyroid rats to 36% in hyperthyroid rats.

Cardiac output and its distribution during diving in the rat

The diving response was produced by submerging the head of the unanesthetized rat for 60 s, while it was confined in a mesh-wired cone. Heart rate and cardiac output decreased by 73% and 74% from the predive values, respectively, indicating insignificant change in stroke volume. Central systemic arterial blood pressure rose by 22% during diving and a fourfold increase in total peripheral resistance was observed. Blood flow to the coronary, cerebral, and bronchial circulations remained unchanged while a 95% reduction in the intestine and the spleen, a 97% reduction in the kidney, and greater than 99% reduction in the tail and skin were observed during diving. The blood flow reduction from predive values ranged from 50% for liver and skeletal muscle to 75% for the adrenals and 65% for the diaphragm. The redistribution of the drastically reduced cardiac output during head immersion in the rat is similar to that reported for diving mammals. It is suggested that the rat may serve as a useful cardiovascular model for further studies of the diving response in mammals.