Tumor-imaging potential of liposomes loaded with In-111-NTA: biodistribution in mice

EMT6 tumors in BALB/c mice have been successfully imaged with small (less than 0.1 mu), unilamellar lipid vesicles (SUVs) loaded with In-111 nitrilotriacetic acid (In-111 NTA). Neutral SUVs prepared from distearoyl phosphatidylcholine (DSPC) and cholesterol (CH) (ratio 2:1) delivered sufficient radioactivity to allow tumor visualization 24 hr after i.v. injection; so did positively and negatively charged SUVs with the ratio 4:1:1 for DSPC:CH:X, were X was stearylamine or dicetyl phosphate. Other SUVs containing a 6-aminomannose or 6-aminomannitol derivative of cholesterol did not cause significant tumor accumulation of In-111 NTA, and tumor images were not readily discernible. The maximum tumor-associated radioactivity, 18.5% of injected dose per gram of tissue, was achieved with neutral SUVs. This level of tumor-associated In-111 was over 4 times that observed when unencapsulated In-111 NTA was injected. Neutral SUVs also gave the lowest specific activities in the liver and spleen (14.6% and 18.8% of dose respectively).

Effect of changes in shoot carbon-exchange rate on soybean root nodule activity

The effect of short- and long-term changes in shoot carbon-exchange rate (CER) on soybean (Glycine max [L.] Merr.) root nodule activity was assessed to determine whether increases in photosynthate production produce a direct enhancement of symbiotic N(2) fixation. Shoot CER, root + nodule respiration, and apparent N(2) fixation (acetylene reduction) were measured on intact soybean plants grown at 700 microeinsteins per meter per second, with constant root temperature and a 14/10-hour light/dark cycle. There was no diurnal variation of root + nodule respiration or apparent N(2) fixation in plants assayed weekly from 14 to 43 days after planting. However, if plants remained in darkness following their normal dark period, a significant decline in apparent N(2) fixation was measured within 4 hours, and decreasing CO(2) concentration from 320 to 90 microliters CO(2) per liter produced diurnal changes in root nodule activity. Increasing shoot CER by 87, 84, and 76% in 2-, 3-, and 4-week-old plants, respectively, by raising the CO(2) concentration around the shoot from 320 to 1,000 microliters CO(2) per liter, had no effect on root + nodule respiration or acetylene-reduction rates during the first 10 hours of the increased CER treatment. When the CO(2)-enrichment treatment was extended in 3-week-old plants, the only measured parameter that differed significantly after 3 days was shoot CER. After 5 days of continuous CO(2) enrichment, root + nodule respiration and acetylene reduction increased, but such changes reflected an increase in root nodule mass rather than greater specific root nodule activity. The results show that on a 24-hour basis the process of symbiotic N(2) fixation in soybean plants grown under controlled environmental conditions functioned at maximum capacity and was not limited by shoot CER. Whether N(2)-fixation capacity was limited by photosynthate movement to root nodules or by saturation of metabolic processes in root nodules is not known.

Carbon and nitrogen limitations on soybean seedling development

Carbon and nitrogen limitations on symbiotically grown soybean seedlings (Glycine max [L.] Merr.) were assessed by providing 0.0, 1.0, or 8.0 millimolar NH(4)NO(3) and 320 or 1,000 microliters CO(2)/liter for 22 days after planting. Maximum development of the Rhizobium-soybean symbiosis, as determined by acetylene reduction, was measured in the presence of 1.0 millimolar NH(4)NO(3) under both levels of CO(2). Raising NH(4)NO(3) from 0.0 to 8.0 millimolar under 320 microliters CO(2)/liter increased plant dry weight by 251% and Kjeldahl N content by 287% at 22 days after planting. Increasing NH(4)NO(3) from 1.0 to 8.0 millimolar under 320 microliters CO(2)/liter increased total dry weight and Kjeldahl N by 100 and 168%, respectively, on day 22. Raising CO(2) from 320 to 1,000 microliters CO(2)/liter during the same period had no significant effect on Kjeldahl N content of plants grown with 0.0 or 1.0 millimolar NH(4)NO(3). The maximum CO(2) treatment effects were observed in plants supplied with 8.0 millimolar NH(4)NO(3), where dry weight and Kjeldahl N content were increased 64% and 20%, respectively. An increase in shoot CO(2)-exchange rate associated with the CO(2)-enrichment treatment was reflected in a significant increase in leaf dry weight and starch content for plants grown with 1,000 microliters CO(2)/liter under all combined N treatments. These data show directly that seedling growth in symbiotically grown soybeans was limited primarily by N availability. The failure of the CO(2)-enrichment treatment to increase total plant N significantly in Rhizobium-dependent plants indicates that root nodule development and functioning in such plants was not limited by photosynthate production.

Effect of irradiance on development of apparent nitrogen fixation and photosynthesis in soybean

Soybeans grown with 2 millimolar NO(3) (-), which optimized apparent N(2) fixation by Rhizobium symbionts, showed significantly different rates of apparent photosynthesis and C(2)H(2) reduction during seedling development at two irradiances. Those physiological processes were lower for several weeks in plants grown at 1,500 microeinsteins per meter(2) per second than in those exposed to 700 microeinsteins per meter(2) per second. The irradiance-induced retardation was evident in short-term rates of apparent photosynthesis and N(2) fixation, as well as in measures of dry matter and total N accumulation. In spite of their previously inhibited development, plants grown at 1,500 microeinsteins per meter(2) per second were indistinguishable by day 28 from those exposed to 700 microeinsteins per meter(2) per second in terms of whole-shoot CO(2)-exchange rate; by day 35 they were identical in terms of whole-plant C(2)H(2)-reduction rate. On day 38 there was no significant difference in dry weight or N content between treatments. Shifting plants between irradiance treatments on day 21 showed that the higher irradiance also had a short-term inhibitory effect on C(2)H(2) reduction. The fact that 16 millimolar NO(3) (-) prevented the continuous exposure to 1,500 microeinsteins per meter(2) per second from inhibiting apparent photosynthesis suggested that seedlings grown on 2 millimolar NO(3) (-) with Rhizobium were N-limited. Although rates of apparent photosynthesis were similar by day 28, the additional week required to produce equal rates of apparent N(2) fixation between irradiance treatments showed that physiological adaptations of shoots, as well as photosynthesis per se, can affect root nodule activity.

Carbon exchange rates of shoots required to utilize available acetylene reduction capacity in soybean and alfalfa root nodules

The CO(2)-exchange rate required to make full use of available N(2)-fixation capacity, measured as acetylene reduction, was determined in soybean and alfalfa. Carbohydrates of root systems were depleted during a 40-hour dark treatment; then plants were exposed to a 24-hour light period during which different CO(2)-exchange rates were maintained with various CO(2) concentrations. In three- and four-week-old soybeans and four-week-old alfalfa plants, acetylene-reduction capacity was used fully with CO(2)-exchange rates as low as 10 milligrams CO(2) per plant per hour. In six-week-old alfalfa plants, however, acetylene reduction rates increased linearly, and apparent N(2)-fixation capacity was not used fully when CO(2)-exchange rates were higher than 40 milligrams CO(2) per plant per hour. Under the conditions established, the energy cost of N(2) fixation, measured as Delta(respiration of roots + nodules)/Deltaacetylene reduction over dark-treatment values, was 0.453 milligrams CO(2) per micromole C(2)H(4) for all rates of acetylene reduction and for both ages of soybean and alfalfa plants. Thus, root-plus-nodule respiration was not promoted by higher rates of apparent photosynthesis after C(2)H(2)-reduction capacity became saturated, and all available capacity for apparent N(2) fixation had the same energy requirement.

A study of the myocardial depressant factor and its relative influence in drug/alcohol mortality

A shock factor, a low molecular weight peptide, has been isolated from postmortem blood. High levels of this peptide, which depresses the myocardium, were seen in cases where drug overdose or alcoholism, or both, were the cause of death. An elevated myocardial depressant factor (MDF) level also demonstrated in a fire victim and a patient in cardiogenic shock. The peptide analysis was accomplished by using an isolated cat papillary muscle followed by paper chromatographic confirmation. Postmortem electrolytes, alcohol, and various toxic agents were eliminated as causes of myocardial depression in the isolated cat papillary muscle assay. The presence of elevated MDF levels may be significant in the overall death process.

Effects of blood-induced infections of Plasmodium hermani on domestic and wild turkey poults

Experimental blood-induced infections of Plasmodium hermani were studied in young domestic and laboratory-reared wild turkey poults. Anemia, splenomegaly and decreased growth rates were observed, but no mortality due to the malarial infections occurred. It is suggested that malaria, acting in concert with other factors, may contribute to mortality of wild turkey poults in Florida during the first 3 to 4 weeks after hatching.

A perspective on the usefulness of computers in nuclear medicine

A computer system in clinical nuclear medicine has a wide variety of operations which it can perform. These range from simple data acquisition and tabulation to elaborate temporal and spatial reconstructions. Simultaneous recording of physiological data has also expanded the number of nuclear medical studies possible. The multiple-gated cardiac equilibrium analysis is the primary example of this format which has evolved rapidly with the availability of inexpensive central memory. Decreasing size and cost of processor units recently have led to the development of multiple processor systems. In some cases, the peripheral devices have a microprocessor already built in. The total cost of the computer system is essentially dictated by the number of peripheral devices.

Photosynthetic carbon metabolism during leaf ontogeny in Zea mays L.: Enzyme studies

The activities of several enzymes, including ribulose-1,5-diphosphate (RuDP) carboxylase (EC 4.1.1.39) and phosphoenolpyruvate (PEP) carboxylase (EC 4.1.1.31) were measured as a function of leaf age in Z. mays. Mature leaf tissue had a RuDP-carboxylase activity of 296.7 μmol CO2 g(-1) fresh weight h(-1) and a PEP-carboxylase activity of 660.6 μmol CO2 g(-1) fresh weight h(-1). In young corn leaves the activity of the two enzymes was 11 and 29%, respectively, of the mature leaves. In senescent leaf tissue, RuDP carboxylase activity declined more rapidly than that of any of the other enzymes assayed. On a relative basis the activities of NADP malic enzyme (EC 1.1.1.40), aspartate (EC 2.6.1.1) and alanine aminotransferase (EC 2.6.1.2), and NAD malate dehydrogenase (EC 1.1.1.37) exceeded those of both PEP and RuDP carboxylase in young and senescent leaf tissue. Pulse-chase labeling experiments with mature and senescent leaf tissue show that the predominant C4 acid differs between the two leaf ages. Labeling of alanine in senescent tissue never exceeded 4% of the total (14)C remaining during the chase period, while in mature leaf tissue alanine accounted for 20% of the total after 60 s in (12)CO2. The activity of RuDP carboxylase during leaf ontogeny in Z. mays parallels the development of the activity of this enzyme in C3 plants.

Effect of different killing techniques on early labeled photosynthetic products in c(4) plants

The choice of leaf-killing technique was found to affect significantly the distribution of label among early labeled photosynthetic products in two C(4) plants, Portulaca oleracea and Zea mays. The major effect of these procedures was on the amount of amino acids present, particularly alanine, and the ratio of malate to aspartate. Killing Portulaca leaves in alcohol generally results in more alanine and the predominance of malate over aspartate. When the leaves are killed by immediate freezing, however, aspartate contained more radioactivity than malate, and alanine was present in much reduced amounts. The various methods also differ in the relative amounts of C(3) cycle compounds and other, secondary intermediates which were obtained.

The colposuspension operation for urinary incontinence

Forty-two patients with urinary incontinence and related symptoms were treated by colposuspension. Two patients were lost to follow-up and the results of surgery in the remaining 40 patients are presented and discussed. The place of vaginal surgery in women with urinary symptoms is also discussed.

Detection of canine kidney allograft rejection with 51Cr-labeled lymphocytes

Mongrel dogs received transplanted kidneys following total nephrectomy. The whole blood was centrifuged to separate out the lymphocytic fraction, which was tagged with 51Cr. Renal accumulation of 51Cr was followed using imaging detectors. All allograft rejections were accompanied by a simultaneous rise in the count rate. Labeled lymphocytes can be used to detect canine renal rejection, and the authors feel that this technique can be applied to man.