Climate change. Managing forests after Kyoto

The Kyoto protocol aims to reduce carbon emissions into the atmosphere. Part of the strategy is the active management of terrestrial carbon sinks, principally through afforestation and reforestation. In their Perspective, Schulze et al. argue that the preservation of old-growth forests may have a larger positive effect on the carbon cycle than promotion of regrowth.

Cervical discectomy. A prospective analysis of three operative techniques

BACKGROUND

Cervical disc herniation causing neurological compromise is a common affliction. Sophisticated surgical treatments have been developed throughout the twentieth century and are largely successful. Although each procedure has its supporters, it is still unclear if one surgical technique is superior.

METHODS

A prospective trial was designed to evaluate the efficacy of three surgical procedures for the treatment of cervical radiculopathy caused by a unilateral acute herniated cervical disc. Patients were randomized to posterior cervical foraminotomy (FOR), and anterior cervical discectomy with (ACDF), and without (ACD) fusion. Perioperative data, office follow-up and long-term follow-up were used to compare the procedures.

RESULTS

All of the procedures yielded excellent relief of symptoms and signs postoperatively and during follow-up. Operative time and hospital stay were slightly shorter for ACD compared with ACDF and FOR. Reoperations occurred in all groups but there was a trend for higher recurrence at the same level with FOR and recurrence at other levels with ACDF.

CONCLUSION

All three of the procedures were successful for treatment of cervical radiculopathy caused by a herniated cervical disc. Although the numbers in this study were small, none of the procedures could be considered superior to the others. This study suggests that the selection of surgical procedure may reasonably be based on the preference of the surgeon and tailored to the individual patient.

Immunolocalization of progesterone receptors in bovine placentomes throughout mid and late gestation and at parturition

The corpus luteum is the main source of progesterone (P(4)) responsible for maintenance of gestation in cattle. So far it has not been possible to assign any biological role to placental P(4), which contributes only marginally and temporarily to peripheral maternal blood levels. In order to identify possible P(4) target cells within the placenta, placentomes from 150-, 220-, 240-, and 270-day-pregnant cows and from parturient cows (3 animals per group) were screened immunohistochemically for expression of the progesterone receptor (PR). During gestation, PR-positive staining was found exclusively in the nuclei of caruncular stromal cells (CSC; maternal part of the placentome) and of caruncular vascular pericytes. In placentomes from parturient cows, occasional positive nuclear staining was also observed in the walls of small caruncular arteries. The percentage of PR-positive CSC increased slightly from 51.8 +/- 2.6% on Day 150 to 56.2 +/- 5.6% at Day 270 (p < 0.05) and was 58.9 +/- 1.8% at parturition. These results suggest that in pregnant cattle, CSC are under the control of P(4) of placental rather than luteal origin. Thus, whereas luteal P(4) may regulate "coarse" systemic progestational functions in the maternal compartment in the classical hormonal manner, placental P(4) may act as a paracrine factor involved in the local regulation of caruncular growth, differentiation, and functions.

Percutaneous renal biopsy: three years of experience with the biopty gun in 761 cases--a survey of results and complications

From 1.1.1993 to 12.31.1995 we performed 761 consecutive biopsies on 509 non-selected patients. The most frequent diagnoses in 351 biopsies (39.4%) on native kidneys were 262 cases of glomerulonephritis (74.6%) and 167 of so-called benign nephrosclerosis (47.6%). With 410 biopsies (60.6%) on allograft kidneys 219 cases (78%) showed signs of interstitial rejection, 14 cases (5%) vascular and 49 cases (17%) interstitial as well as vascular rejection. Only after 5 biopsies (0.66%) clinical relevant complications (3 perirenal haematomas, 1 AV fistula, 1 vesical tamponade) appeared. Again percutaneous renal biopsy is proven to be a diagnostically efficient and safe tool at the same time even when used in a large number of non-selected patients, so that an ambulant performance may be discussed. The relatively frequent diagnosis of a so-called benign nephrosclerosis seems to indicate the need for an intensified examination of this disease.

Effect of the lectins wheat germ agglutinin (WGA) and Ulex europaeus agglutinin (UEA-I) on the alpha-amylase secretion of rat pancreas in vitro and in vivo

Lectins are able to bind to cholecystokinin (CCK) receptors and other glycosylated membrane proteins. The lectins wheat germ agglutinin (WGA) and Ulex europaeus agglutinin (UEA-I) are used for affinity chromatography to isolate the highly glycosylated CCK-A receptor of pancreatic acinar cells. According to the working hypothesis that lectin binding to the CCK receptor should alter the ligand-receptor interaction, the effect of WGA and UEA-I on CCK-8-induced enzyme secretion was studied on isolated rat pancreatic acini in vitro. In vitro both lectins showed a dosage-dependent inhibition of CCK-8-induced alpha-amylase secretion of acini over 60 min. WGA showed a strong inhibitory effect on amylase secretion, approximately 40%, in vitro. UEA-I caused a smaller, but significant decrease, approximately 20%, in enzyme secretion of isolated acini. Additionally, both lectins inhibited cerulein/secretin- or cerulein-induced pancreatic secretion of rats in vivo, but not after secretin alone. The results are discussed with respect to a possible influence of both lectins on the interaction of CCK or cerulein with the CCK-A receptor.

Internalization of wheat germ agglutinin (WGA) by rat pancreatic cells in vivo and in vitro

The uptake of the lectin wheat germ agglutinin (WGA) by the rat pancreas was studied after intraperitoneal injection of FITC-labelled WGA. Strong fluorescence was seen in the interstitial space of the pancreatic parenchyma and on the basolateral surface of acinar cells after one h. Two or four h after injection there was also a fluorescence inside the acinar cells. After intraparenchymal injection of colloidal gold-labelled WGA into the pancreatic gland in situ or in vitro incubation of isolated rat pancreatic acinar cells with WGA-gold, an internalization of the lectin by receptor mediated endocytosis was observed electron microscopically. Clathrin-coated pits or vesicles could not be observed. The results suggest a direct uptake of WGA from the peritoneum into the gland by diffusion and its binding as well as internalization by the pancreatic acinar cells.

A mutant of melanoma growth stimulating activity does not activate neutrophils but blocks erythrocyte invasion by malaria

Alanine scanning mutagenesis of the charged amino acids of melanoma growth stimulating activity (MGSA) was used to identify specific residues that are involved in binding to the human erythrocyte Duffy antigen/chemokine receptor (DARC) and to the type B interleukin-8 receptor (IL-8RB) on neutrophils. Receptor binding and biological studies with the alanine scan mutants of MGSA demonstrate that MGSA binds to DARC and the IL-8RB through distinct binding regions. One of the MGSA mutants, E6A, binds to human erythrocytes and is able to inhibit malaria invasion as efficiently as wild type MGSA but has a severely reduced ability to bind to or signal through the IL-8RB. Mutant chemokines like E6A could prove to be useful therapeutically for the design of receptor blocking drugs that inhibit erythrocyte invasion by Plasmodium vivax malaria.

Synthesis and beta-lactamase-mediated activation of a cephalosporin-taxol prodrug

BACKGROUND

Enzyme-activatable prodrugs in conjunction with antibody-enzyme fusion proteins may enhance the anti-tumor efficacy of antibodies and reduce the toxic side effects of conventional chemotherapeutics. Cephalosporins have proven to be highly versatile triggers for the enzymatic activation of such prodrugs.

RESULTS

A cephem prodrug of taxol (PROTAX) was synthesized by substituting the C-3' position of cephalothin with 2'-(gamma-aminobutyryl) taxol. Hydrolysis of PROTAX by beta-lactamase rapidly released 2'-(gamma-aminobutyryl) taxol (kcat/K(M) = (1.4 +/- 0.1) x 10(5) s-1 M-1), which yielded taxol following intramolecular displacement. PROTAX is inactive in a microtubule assembly assay in vitro but has similar activity to taxol following prolonged activation with beta-lactamase. PROTAX is approximately 10-fold less toxic than taxol against SK-BR-3 breast tumor cells in vitro but has activity approaching that of taxol following prolonged activation with a fusion protein comprising beta-lactamase fused to a tumor-targeting antibody fragment.

CONCLUSIONS

Tubulin polymerization activity is abolished and cytotoxicity is reduced in the PROTAX prodrug compared to taxol. Activation of PROTAX by beta-lactamase followed by self-immolation restores the activity of PROTAX to that of free taxol.

Development of anti-p185HER2 immunoliposomes for cancer therapy

The product of the HER2 protooncogene, p185HER2, represents an attractive target for cancer immunotherapies. We have prepared anti-p185HER2 immunoliposomes in which Fab' fragments of a humanized anti-p185HER2 monoclonal antibody with antiproliferative properties (rhuMAb-HER2) were conjugated to either conventional or sterically stabilized liposomes. These immunoliposomes bind specifically to p185HER2-overexpressing breast cancer cells (SK-BR-3 and BT-474). High-affinity binding of anti-p185HER2 immunoliposomes is comparable to that of free rhuMAbHER2-Fab' or the intact antibody. Empty immunoliposomes inhibit the culture growth of p185HER2-overexpressing breast cancer cells, and this antiproliferative effect is superior to that of free rhuMAbHER2-Fab', indicating that liposomal anchoring of these anti-p185HER2 Fab' fragments enhances their biological activity. Efficient internalization of anti-p185HER2 immunoliposomes, demonstrated by light and electron microscopy, occurs by receptor-mediated endocytosis via the coated pit pathway and also possibly by membrane fusion. Doxorubicin-loaded anti-p185HER2 immunoliposomes are markedly and specifically cytotoxic against p185HER2-overexpressing tumor cells in vitro. Anti-p185HER2 immunoliposomes administered in vivo in Scid mice bearing human breast tumor (BT-474) xenografts can deliver doxorubicin to tumors. These results indicate that anti-p185HER2 immunoliposomes are a promising therapeutic vehicle for the treatment of p185HER2-overexpressing human cancers.

Development of a humanized disulfide-stabilized anti-p185HER2 Fv-beta-lactamase fusion protein for activation of a cephalosporin doxorubicin prodrug

The humanized anti-p185HER2 antibody, humAb4D5-8, has completed Phase II clinical trials for p185HER2-overexpressing breast cancer. Here, this antibody is used as a building block to engineer a disulfide-linked Fv (dsFv) beta-lactamase fusion protein for use in antibody-dependent enzyme-mediated prodrug therapy using cephalosporin-based prodrugs. Three Fv variants were designed with an interchain disulfide bond buried at the VL/VH interface and secreted from Escherichia coli. One variant, dsFv3 (VL L46C VH D101C0, has similar affinity for antigen (Kd = 0.7 nM) as the wild-type Fv and was used to construct a fusion protein in which beta-lactamase, RTEM-1, is joined to the carboxy terminus of VH. The dsFv3-beta-lactamase fusion protein secreted from E. coli efficiently activates a cephalothin doxorubicin prodrug (PRODOX, kcat/km = 1.5 x 10(5) s-1 M-1). PRODOX is approximately 20-fold less toxic than free doxorubicin against breast tumor cell lines SK-BR-3 and MCF7, which express p185HER2 at elevated and normal levels, respectively. Prebinding the dsFv3-beta-lactamase fusion protein specifically enhances the toxicity level of PRODOX to that of doxorubicin against SK-BR-3 but not MCF7 cells. The fusion protein retains both antigen-binding plus kinetic activity in murine serum and is cleared rapidly as judged by pharmacokinetic analysis in nude mice (initial and terminal half-lives of 0.23 and 1.27 h, respectively). Development and characterization of the dsFv3-beta-lactamase fusion protein is an important step toward targeted prodrug therapy of p185HER2-overexpressing tumors.

Non-enzymatic glycation of histones

2-(2-Furoyl)-5-(2-furanyl)-1H-imidazole (FFI) is detected in total histones and the lysine-rich histone 1 fraction isolated from calf thymus after in vitro glycation and hydrolysis with HCl, using gas chromatographic/mass spectrometric analysis. The finding suggests that glucose is bound to the epsilon-amino groups of the lysine residues of the histones. No FFI is monitored in native histone samples.

A high omega 3 fatty acid diet alters fatty acid composition of heart, liver, kidney, adipose tissue and skeletal muscle in swine

The fatty acid profiles and total lipid contents of two skeletal muscles, adipose tissue, heart, liver and kidney of swine fed a diet rich in omega 3 (n-3) fatty acids (i.e., 5% fish oil) was investigated. These values were compared to those determined for animals which were fed an equal caloric diet low in n-3 fatty acids (i.e., 5% coconut oil). All supplementations were given over a 13-week period. The lipids were extracted with chloroform-methanol, trans-esterified and the relative fatty acid methyl-esters concentrations were determined using capillary gas chromatography. The fish oil diet significantly enhanced the relative amounts of n-3 fatty acids (i.e., eicosapentaenoic acid and docosahexaenoic acid) in all tissues examined. In the heart, liver and kidney, the increases in n-3 fatty acids were compensated by decreases primarily in arachidonic acid, but in the other tissues the contents of lauric and myristic acids were also reduced. In general, the n-3 fatty acid contents were 40-165% higher in the animals fed the fish oil. Supplementation of n-3 fatty acids in swine induced a significant incorporation of these fatty acids throughout the body, however the extent of this incorporation differed between tissues perhaps due to tissue-specific metabolic pathways.

Analysis of polyunsaturated fatty acids in blood serum after fish oil administration

Free and total fatty acids in the blood serum of patients with hyperlipoproteinemia have been analysed as their methyl esters by capillary gas chromatography using an FFAP column. In one-step reactions the free fatty acids in serum react with methanol-acetyl chloride (50:1, v/v) at 25 degrees C, the total fatty acids (free plus esterified) are transesterified with methanol-toluene-acetyl chloride (8:2:1, v/v) at 100 degrees C. The quantification of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) is based on an internal standard (13,16,19-docosatrienoic acid) and on calibration standards. Under normal diet the concentrations of EPA and DHA are as follows (mean +/- S.D., n = 27): free EPA, 0.2 +/- 0.1 mg/dl; free DHA, 0.6 +/- 0.2 mg/dl; total EPA, 3.6 +/- 2.1 mg/dl; total DHA 11.4 +/- 3.1 mg/dl. Under a fish oil intake of 9 g per day, free and total EPA concentrations rise by ca. five- to six-fold, and free and total DHA concentrations by ca. two-fold.

Use of intravenous immunoglobulin in chronic lymphocytic leukemia. A brief review

Chronic lymphocytic leukemia (CLL) is a disorder with multiple defects leading to an increased susceptibility to infection. Hypogammaglobulinemia is present in about 20% to 70% of patients with CLL. Intravenous immunoglobulin (IVIG) supplementation (400 mg/kg body weight every 3 weeks) prevented bacterial infections in these patients. An ongoing study is being conducted to compare doses of 250 mg/kg/mo with those of 500 mg/kg/mo in 36 patients included so far. As of this writing, the rate of infection in the two treatment groups was not significantly different, and no substantial loss of protection against bacterial infection was found in the lower-dose group. It seems likely that the lower dose is almost as effective as the standard therapy. If this is so, cost savings would be substantial.

The community ecology of diabetes patient classification and practice characteristics

We examined the clinical and epidemiologic characteristics of diabetic subjects ascertained from five different sources (hospital, private practice, specialist practice, nursing home, and prevalence survey) in a medium-sized upstate New York community. Patients were categorized using the National Diabetes Data Group classification (based on weight and insulin requirement) and using an alternative clinical classification scheme based on age at onset and insulin use. Both classifications demonstrate marked differences in the distribution of diabetic subjects. Those seen in general medical practice reflect the prevalent population and tend to have fewer complications and less insulin requirement. Those seen in specialist practice or in hospital have higher complication frequencies. Thus, the source of patients may determine the epidemiologic picture of the disease, as well as the practitioners' perceptions. Use of the clinical classification scheme helps to identify a subgroup of diabetic subjects--those with onset past the age of 25 yr who use insulin--at greatest risk of complications. Further investigation of high-risk groups is warranted, particularly for the implementation and evaluation of diabetes control programs.