Quantitative pp65 antigenemia in the diagnosis of cytomegalovirus disease: prospective assessment in a cohort of solid organ transplant recipients

OBJECTIVES

To assess the accuracy of quantitative pp65 antigenemia (pp65Ag) in the diagnosis of CMV disease, in a cohort of solid-organ transplant recipients.

METHODS

Prospective observational study during the first 6 months following transplantation, with determination of pp65Ag at weeks 2, 4, 6, 8, 10, 11, 12, 14 and 16. Sensitivity (S), specificity (E), positive and negative predictive values (PPV, NPV), and the optimal cut-off point for diagnosing CMV disease, were determined.

RESULTS

The cohort consisted of 35 liver, 26 renal and 12 heart graft recipients. Thirteen (17.2%) were seronegative and received a seropositive graft. Of 583 blood samples, pp65Ag was positive in 109 (18.7%) from 37 patients (51%). Twenty-two patients developed CMV disease (0.3 episodes/patient); gastrointestinal disease was the most frequent (15 episodes), followed by viral syndrome (3 episodes). Patients with positive pp65Ag had a relative risk for CMV disease of 6.19 [IC95%=1.99-19.04], (P=.0001). Diagnostic values of pp65Ag were: S=86%, E=65%, PPV=51%, NPV=92%. The cut-off of > or =10 infected cells/10(5), at weeks 2, 4, 6 and 8 obtained the best PPV (0, 67, 91 and 54%), and NPV (47, 52, 67 and 50%).

CONCLUSIONS

In the studied population, the presence of positive pp65Ag was associated with a high risk of developing CMV disease, and the most useful cut-off point for the diagnosis was > or =10 infected cells/10(5).

Laboratory investigation into the development of resistance of Daphnia magna to the herbicide molinate

Daphnia magna (F0 generation) was exposed to different sublethal molinate concentrations (0, 3.77, 4.71, 6.28, 9.42, and 18.85 mg/L) during 21 days. Chronic toxicity tests, using the same herbicide concentrations, were also carried out during 21 days using neonates of F1 first brood (F1-1st) and F1 third brood (F1-3rd) offspring generations from the parentals (F0) preexposed to the herbicide. Finally, offspring (from F1-1st and F1-3rd broods) were transferred to herbicide-free medium during a 21-day recovery period. The alga Nannochloris oculata (5 x 10(5) cells/mL) was used as food in all the experiments. The effect of molinate on survival, reproduction, and growth was monitored for the selected daphnid generations. The parameters used to evaluate herbicide effect on reproduction were mean total young per female, mean brood size, time to first reproduction, mean number broods per female, and intrinsic rate of natural increase (r). Survival and growth (body length) were also determined after 21 days of exposure to molinate. Reproduction was significantly reduced when molinate concentration was increased in the medium. This effect was higher in the parental (F0) daphnids than in the F1-1st and F1-3rd offspring. In the recovery study, reproduction was still reduced in F1 generation daphnids (1st and 3rd), but only in those animals from parentals exposed to the highest molinate concentrations. The decreased with increasing concentrations of molinate in daphnids from the parental generation (F0). Significant differences were also found in daphnids from the F1 generation (exposure). The growth of the exposed organisms (F0 and F1) decreased, although the greatest decrease was found in the parental animals (F0) (25%) exposed to 9.42 mg/L molinate. F1 daphnids (1st and 3rd broods) from the recovery period did not show any significant difference in their growth after 21 days of study. Finally, survival was not affected after exposure to the selected molinate concentrations except in those daphnids from the F0 generation in which survival decreased 51% and 78% at the highest herbicide concentrations tested (9.42 and 18.85 mg/L). Our results suggest that the offspring daphnids seem to be adaptated to the herbicide molinate, showing more longevity and reproduction than their parentals.

Silymarin induces recovery of pancreatic function after alloxan damage in rats

Alloxan has been widely used to produce experimental diabetes mellitus syndrome. This compound causes necrosis of pancreatic beta-cells and, as is well known, induces oxidant free radicals which play a relevant role in the etiology and pathogenesis of both experimental and human diabetes mellitus. Previously we have reported hypoglycemic and antilipoperoxidative actions of silymarin in serum and pancreatic tissue respectively. The aim of this study was to test whether silymarin could reduce the hyperglycemia and revert the pancreatic damage in alloxan treated rats, tested with silymarin in two protocols: using both compounds simultaneously for four or eight doses, or using the compound 20 days after alloxan administration for 9 weeks. Serum glucose and insulin were determined, and pancreatic fragments were used for histology and insulin immunohistochemistry. Pancreatic islets were isolated to assess insulin and Pdx1 mRNA expression by RT-PCR. Our results showed that 72 hours after alloxan administration, serum glucose increased and serum insulin decreased significantly, whereas pancreatic tissue presented morphological abnormalities such as islet shrinkage, necrotic areas, loss of cell organization, widespread lipoid deposits throughout the exocrine tissue, and loss of beta cells, but insulin and glucagon immunoreactivity was scattered if any. In contrast the pancreatic tissue and both insulin and glucose serum levels of rats treated with silymarin were similar to those of control animals. In addition, insulin and glucagon immunoreactive cells patterns in Langerhans islets were also normal, and normal insulin and Pdx1 mRNA expression patterns were detected during pancreatic recovery in Langerhans islets. The overall results suggest that silymarin induces pancreatic function recovery demonstrated by insulin and glucagon expression protein and normoglycemia after alloxan pancreatic damage in rats.

Enriched protein diet-modified ghrelin expression and secretion in rats

Gastrointestinal (GI) integrity and function are regulated by nutrition and growth factors. The discovery of ghrelin, a natural growth hormone (GH) secretagogue produced by the gastrointestinal (GI) tract, is a potential link between diet and growth signals. The aim of this study was to evaluate macronutrient effect on ghrelin expression and secretion in addition to some possible function in intestinal trophic status. Wistar rats were fed a high-carbohydrate, high-protein (HP), high-fat or standard (St) diet. Animals received the same daily food volume and caloric intake. After 7 days, animals were fasted for 24 h and blood and tissue samples were obtained just before feeding or at 2 or 6 h after feeding. Fasting high-protein-fed rats had higher ghrelin plasma levels than with rats fed the high-carbohydrate, high-fat or standard diets. Two-hours after refeeding, ghrelin plasma levels had decreased in all groups with a slight recovery at 6 h after refeeding, except in the high-protein group. Ghrelin plasma levels in rats fed with the high-protein diet correlated negatively with their GH and insulin-like growth factor 1 (IGF-1) plasma concentrations which were also the lowest among the study groups. In conclusion, ghrelin secretion was nutritionally manipulated because a protein-enriched diet increased its levels.

Tissue production of pro-inflammatory cytokines (IL-1 , TNF and IL-6) correlates with the intensity of the systemic inflammatory response and with corticosteroid requirements in giant-cell arteritis

OBJECTIVES

To investigate proinflammatory cytokine expression in temporal arteries from patients with giant-cell arteritis (GCA) and to analyse its relationship with the intensity of the initial systemic inflammatory reaction and response to corticosteroid therapy.

METHODS

Quantification of interleukin-1beta (IL-1beta), tumor necrosis factor alpha (TNFalpha), and interleukin-6 (IL-6) mRNA by real-time quantitative PCR in temporal artery samples from 36 patients with biopsy-proven GCA and 11 controls. Immunohistochemical detection of IL-1beta, TNFalpha, and IL-6 in temporal artery sections from 74 patients with GCA and 15 controls. Clinical and biochemical parameters of inflammation as well as the time (weeks) required to reach a maintenance prednisone dose <10 mg/day were recorded.

RESULTS

IL-1beta (13.8 +/- 2.5 vs 5.4 +/- 1.3 relative units, P = 0.012) and IL-6 transcripts (34 +/- 13.7 vs 7.8 +/- 4.5 relative units, P = 0.034) were significantly more abundant in patients with a strong systemic inflammatory response compared with those with no inflammatory parameters. Immunohistochemical scores for IL-1beta (2.7 +/- 0.3 vs 1.9 +/- 0.2, P = 0.018), TNFalpha (3.2 +/- 0.2 vs 2.4 +/- 0.3, P = 0.028) and IL-6 (3 +/- 0.2 vs 2.1 +/- 0.3, P = 0.023) were also significantly higher in patients with strong systemic inflammatory reaction. A significant correlation was found between the amount of tissue TNFalpha mRNA and the time required to reach a maintenance dose of prednisone <10 mg/day (r = 0.586, P = 0.001).

CONCLUSION

GCA patients with a strong systemic inflammatory response, who have been previously shown to be more resistant to corticosteroid therapy, have elevated tissue expression of proinflammatory cytokines IL-1beta, TNFalpha and IL-6. High production of TNFalpha is associated with longer corticosteroid requirements.

[Cytokines value as a sepsis and mortality predictor in elderly patients with fever]

BACKGROUND AND OBJECTIVE

Proinflammatory cytokines (IL-1beta, IL-6, TNF-alpha) are excellent predictive factors of tissue damage, inflammation and infection. However, there is not sufficient data about their usefulness in elderly patients with acute septic pathology. Our objective was to identify the cytokines related to bacteremia and those that predicted a bad prognosis in elderly patients.

PATIENTS AND METHOD

Prospective study carried out during 1999. Patients aged >= 60 years with temperature >= 38 C admitted to the emergency ward. We determined IL-1beta, IL-6, TNF-alpha and C-reactive protein (CRP); cultures were done according to the infectious source. On the 4th day, cytokines and CRP were recorded again. The follow-up was completed until cure or death.

RESULTS

50 patients were included (29 males). Median age was 75.6 (SD: 8.98). The etiology was infectious in 44 (88%): respiratory in 29 (66%), urinary in 8 (18%) and other sources in 7. Thirteen patients had bacteremia (32%): Escherichia coli (4), Streptococcus pneumoniae (5) and others (4). Ten patients died (20%). Median values on admission were CRP : 6.67 mg/dl (NV 0.8), TNF-alpha: 29 pg/ml (NV 0-20), IL-1beta: 7 pg/ml (NV 15) and IL-6: 121 pg/ml (NV 5). 4th day values were: 4.23 mg/dl, 22 pg/ml, 1 pg/ml and 41 pg/ml, respectively. The levels of IL-1b in the 2nd determination were significantly lower in females (p = 0.019). Initial TNF-alpha (p = 0.033), IL-1beta (p = 0.013) and IL-6 (p = 0.031) values were significantly higher in bacteremia patients. IL-6 values on the 4th day were higher in patients who died (p = 0.06). In patients who died, IL-6 levels were higher in the 2nd determination (p = 0.09).

CONCLUSIONS

Median values of all cytokines were higher in the bacteremia population. Patients who died showed higher levels of IL-6 on the 4th day.

Coupled BAS and anoxic USB system to remove urea and formaldehyde from wastewater

Wastewater containing formaldehyde and urea was treated using a coupled system consisting of a biofilm airlift suspension (BAS) reactor and an anoxic upflow sludge blanket (USB) reactor. The anoxic USB reactor was used to carry out denitrification and urea hydrolysis, while the BAS reactor was used to carry out nitrification. In a first step, individual experiments were carried out to investigate the effects of both compounds on the nitrifying and denitrifying biomass. The BAS reactor was fed with a synthetic medium containing 500 mg N-NH4(+)l(-1) and 100mg N-urea l(-1), that were added continuously to this medium. Neither urea hydrolysis nor inhibition of nitrification was observed. Nitrification efficiency decreased when formaldehyde was fed during shocks at concentrations of 40, 80 and 120 mg C-formaldehyde l(-1). The anoxic USB reactor was fed with a synthetic medium containing nitrate, formaldehyde and urea. Concentrations of formaldehyde in the reactor of 100-120 mg C-formaldehyde l(-1) caused a decrease in the denitrification and urea hydrolysis rates. In a second step, the coupled system was operated at recycling ratios (R) of 3 and 9. Fed C/N ratios of 0.58, 1.0 and 1.5 g C-formaldehyde g(-1) N-NH4(+) were used for every recycling ratio. The maximum nitrogen removal percentages were achieved at a C/N ratio of 1.0 g C-formaldehyde g(-1) N-NH4(+) for both recycling ratios. A fed C/N ratio of 1.5 g C-formaldehyde g(-1) N-NH4(+) caused a decrease in the efficiency of the system with respect to nitrogen removal, due to the presence of formaldehyde in the BAS reactor, which decreased the nitrification. Formaldehyde was completely removed in the BAS reactor and a heterotrophic layer formed around the nitrifying biofilm.

Multicenter study evaluating a dual policy of postorchiectomy surveillance and selective adjuvant single-agent carboplatin for patients with clinical stage I seminoma

BACKGROUND

After decades of irradiation as standard therapy for clinical stage I testicular seminoma, alternative treatment approaches have emerged including postorchiectomy surveillance and adjuvant chemotherapy. This study was performed to assess a dual policy of surveillance and selective single-agent carboplatin (for high-risk cases) in a multicenter setting.

PATIENTS AND METHODS

From 1994 to 1999, 203 patients with stage I seminoma were included. Sixty (29.6%) were considered poor-risk cases (i.e. with vascular invasion and/or pathological tumor stage pT2 or greater) and received two courses of adjuvant carboplatin, whereas 143 (70.4%) without risk criteria underwent close surveillance.

RESULTS

Median follow-up was 52 months (range 14-92). Relapses were observed in two (3.3%) patients treated with carboplatin and in 23 patients (16.1%) on surveillance, with a median time to recurrence of 11 months (range 3.9-39.6). All relapsing patients were rendered disease-free, mainly with cisplatin-based chemotherapy. Four patients died from tumor-unrelated causes. Actuarial 5-year overall survival was 96.7% and cause-specific survival was 100%. Five-year disease-free survival was 83.5% for patients on surveillance, and 96.6% for those receiving carboplatin.

CONCLUSIONS

This dual treatment policy is feasible in a multicenter setting and preserves 70% of patients from adjuvant chemotherapy. Single-agent carboplatin is effective in reducing the relapse rate in patients with high-risk stage I seminoma. A better definition of local risk features would probably improve patient selection, thus minimizing the incidence of recurrences on surveillance.

Analysis of patient flow in the emergency department and the effect of an extensive reorganisation

OBJECTIVES

To evaluate the different internal factors influencing patient flow, effectiveness, and overcrowding in the emergency department (ED), as well as the effects of ED reorganisation on these indicators.

METHODS

The study compared measurements at regular intervals of three hours of patient arrivals and patient flow between two comparable periods (from 10 February to 2 March) of 1999 and 2000. In between, a structural and staff reorganisation of ED was undertaken. The main reason for each patient remaining in ED was recorded and allocated to one of four groups: (1) factors related to ED itself; (2) factors related to ED-hospital interrelation; (3) factors related to hospital itself; and (4) factors related to neither ED nor hospital. The study measured the number of patients waiting to be seen and the waiting time to be seen as effectiveness markers, as well as the percentage of time that ED was overcrowded, as judged by numerical and functional criteria.

RESULTS

Effectiveness of ED was closely related with some ED related and hospital related factors. After the reorganisation, patients who remained in ED because of hospital related or non-ED-non-hospital related factors decreased. ED reorganisation reduced the number of patients waiting to be seen from 5.8 to 2.5 (p<0.001) and waiting time from 87 to 24 minutes (p<0.001). Before the reorganisation, 31% and 48% of the time was considered to be overcrowded in numerical and functional terms respectively. After the reorganisation, these figures were reduced to 8% and 15% respectively (p<0.001 for both).

CONCLUSIONS

ED effectiveness and overcrowding are not only determined by external pressure, but also by internal factors. Measurement of patient flow across ED has proved useful in detecting these factors and in being used to plan an ED reorganisation.

Potassium efflux induced by a new lactoferrin-derived peptide mimicking the effect of native human lactoferrin on the bacterial cytoplasmic membrane

A 31-amino acid synthetic peptide (NH(2)-FFSASCVPGADKGQFPNLCRLCAGTGENKCA-COOH) was chemically synthesized based on the amino acid sequence of a region of human lactoferrin homologous to other sequences present in the N- and C-lobes of all members of the transferrin family proteins. The peptide, termed kaliocin-1, and lactoferrin showed a bactericidal effect in assays performed in low-ionic-strength conditions. This is the first time that it is shown that the antimicrobial effect of lactoferrin depends on the extracellular cation concentration. The antimicrobial effect of kaliocin-1 was lower than that of human lactoferrin, but their activities were inhibited by Na(+) or K(+) in a cation concentration-dependent manner. In addition, the peptide was able to mimic native lactoferrin, inducing K(+)-efflux and a selective dissipation of the transmembrane electrical potential of Escherichia coli cells without causing extensive damage to the outer and inner bacterial membranes. In contrast, the peptide, but not lactoferrin, was able to permeabilize different ions through liposomal membranes. The hypothetical interaction of kaliocin-1 with a bacterial membrane compound is discussed based in the different ion flux induced on cellular and artificial membranes as well as data from circular dichroism assays. Kaliocin-1 was not cytotoxic and could be a suitable model for the design of analogs able to mimic the antibacterial effect of human lactoferrin.

Valor de las citocinas proinflamatorias como factor de predicción de sepsis y mortalidad en el anciano con fiebre

BACKGROUND AND OBJECTIVE

Proinflammatory cytokines (IL-1beta, IL-6, TNF-alpha) are excellent predictive factors of tissue damage, inflammation and infection. However, there is not sufficient data about their usefulness in elderly patients with acute septic pathology. Our objective was to identify the cytokines related to bacteremia and those that predicted a bad prognosis in elderly patients.

PATIENTS AND METHOD

Prospective study carried out during 1999. Patients aged >= 60 years with temperature >= 38 C admitted to the emergency ward. We determined IL-1beta, IL-6, TNF-alpha and C-reactive protein (CRP); cultures were done according to the infectious source. On the 4th day, cytokines and CRP were recorded again. The follow-up was completed until cure or death.

RESULTS

50 patients were included (29 males). Median age was 75.6 (SD: 8.98). The etiology was infectious in 44 (88%): respiratory in 29 (66%), urinary in 8 (18%) and other sources in 7. Thirteen patients had bacteremia (32%): Escherichia coli (4), Streptococcus pneumoniae (5) and others (4). Ten patients died (20%). Median values on admission were CRP : 6.67 mg/dl (NV 0.8), TNF-alpha: 29 pg/ml (NV 0-20), IL-1beta: 7 pg/ml (NV 15) and IL-6: 121 pg/ml (NV 5). 4th day values were: 4.23 mg/dl, 22 pg/ml, 1 pg/ml and 41 pg/ml, respectively. The levels of IL-1b in the 2nd determination were significantly lower in females (p = 0.019). Initial TNF-alpha (p = 0.033), IL-1beta (p = 0.013) and IL-6 (p = 0.031) values were significantly higher in bacteremia patients. IL-6 values on the 4th day were higher in patients who died (p = 0.06). In patients who died, IL-6 levels were higher in the 2nd determination (p = 0.09).

CONCLUSIONS

Median values of all cytokines were higher in the bacteremia population. Patients who died showed higher levels of IL-6 on the 4th day.

Distribution of HLA-DRB1 genes in patients with sporadic ankylosing spondylitis in the south of Spain

OBJECTIVE

To evaluate the relationship between the presence of different HLA-DRB1 genes and predisposition to develop a sporadic form of ankylosing spondylitis (AS) in a demographically well-defined population.

METHODS

One hundred fifteen selected patients with sporadic (non-familial) forms of AS from six different cities and 748 bone marrow donors as control group. All individuals were typed for HLA-B27 by flow cytometry with monoclonal antibodies and PCR -SSP, as well as for HLA-DRB using the Dynal ELI SSO HLA-DRB Test (Dynal AS, Oslo, Norway). The Inno-Lipa DRB Decoder (Innogenetics NV Zwijndrecht, Belgium), was used for high-resolution HLA-DRB typing.

RESULTS

The presence of the DRB1*01 antigen in the studied population is significantiy higher in B27 positive healthy individuals (bone marrow donors) than in B27 positive AS patients; also, DRB1*01 is higher in B27 negative AS patients than 827 negative controls. The frequency of DRB1*03 is higher in B27 negative controls than B27 negative AS patients.

CONCLUSION

The results of this study suggest that DRB1*01 antigens might be involved in the development of sporadic forms of ankylosing spondylitis in HLA-B27 negative individuals in the studied area.

Solid dispersions of diflunisal-PVP: polymorphic and amorphous states of the drug

Coprecipitates of diflunisal and polyvinylpyrrolidone (PVP K15, K30, and K90) and physical mixtures were studied using x-ray diffraction analysis, infrared (IR) spectroscopy, differential scanning calorimetry (DSC), and hot-stage microscopy. X-ray diffraction results revealed an almost amorphous state, even in coprecipitates with a high content of drug, next to 70%, which was independent of the polymer molecular weight. The IR spectra of 70:30 drug-PVP solid dispersions suggest the formation of diflunisal-PVP hydrogen bonds. For 70:30 drug-polymer ratio, the physical mixture showed linear dissolution kinetics of free crystals, but the corresponding coprecipitates exhibit two different dissolution processes. When the 25:75 drug-polymer dispersion is analyzed by hot-stage microscopy, only solid plates of PVP are observed; the absence of drug particles may be due to a molecular dispersion of the drug into the polymer. Moreover, polymorphic changes of diflunisal were detected in the solid dispersions in comparison with the corresponding physical mixtures, which are always formed by polymorph II. At high concentrations of drug (75:25 and 80:20), x-ray diffraction patterns of solid dispersions showed the partial recrystallization of the drug, displaying the main diffraction peaks of polymorph I when ethanol was used as coprecipitation solvent, whereas diflunisal form IV was obtained in chloroform.

Nitrification in saline wastewater with high ammonia concentration in an activated sludge unit

A nitrifying activated sludge reactor fed with a high salinity medium was operated efficiently at ammonia loading rates between 1 and 4 g NH4+ -N l(-1) d(-1). The system became completely inefficient at inlet salt concentrations higher than 525 mM due to the mixed inhibition effect of salts and ammonia. The final product was mainly nitrate although dissolved oxygen limitations caused sporadic ammonia and nitrite accumulations. Specific nitrifying activity decreased due to the saline effect. A set of activity tests showed that in the continuous reactor non-adapted biomass is rather more sensitive than biomass to the saline effect. Physical properties of biomass in the reactor (sludge volumetric index and zone settling velocity) were not affected by the saline concentration, a biomass concentration of 20 gVSS l(-1) was achieved.

Prevalence and clinical importance of sleep apnea in the first night after cerebral infarction

OBJECTIVE

To determine the prevalence of sleep apnea (SA) during the first night after hemispheric ischemic stroke and its influence on clinical presentation, course, and functional outcome at 6 months.

METHODS

The first night after cerebral infarction onset, 50 patients underwent polysomnography (PSG) followed by oximetry during the next 24 hours. Neurologic severity and early worsening were assessed by the Scandinavian Stroke Scale and outcome by the Barthel Index. Patients were evaluated on admission, on the third day, at discharge, and at 1, 3, and 6 months.

RESULTS

There were 30 males and 20 females with a mean age of 66.8 +/- 9.5 years. Latency between stroke onset and PSG was 11.6 +/- 5.3 hours. Thirty-one (62%) subjects had SA (apnea-hypopnea index [AHI] > or = 10). Of these, 23 (46%) had an AHI > or =20 and 21 (42%) an AHI > or =25. Sleep-related stroke onset occurred in 24 (48%) patients and was predicted only by an AHI > or =25 on logistic regression analysis. SA was related to early neurologic worsening and oxyhemoglobin desaturations but not to sleep history before stroke onset, infarct topography and size, neurologic severity, or functional outcome. Early neurologic worsening was found in 15 (30%) patients, and logistic regression analysis identified SA and serum glucose as its independent predictors.

CONCLUSIONS

SA is frequent during the first night after cerebral infarction (62%) and is associated with early neurologic worsening but not with functional outcome at 6 months. Cerebral infarction onset during sleep is associated with the presence of moderate to severe SA (AHI > or = 25).

The genome sequence of Schizosaccharomyces pombe

We have sequenced and annotated the genome of fission yeast (Schizosaccharomyces pombe), which contains the smallest number of protein-coding genes yet recorded for a eukaryote: 4,824. The centromeres are between 35 and 110 kilobases (kb) and contain related repeats including a highly conserved 1.8-kb element. Regions upstream of genes are longer than in budding yeast (Saccharomyces cerevisiae), possibly reflecting more-extended control regions. Some 43% of the genes contain introns, of which there are 4,730. Fifty genes have significant similarity with human disease genes; half of these are cancer related. We identify highly conserved genes important for eukaryotic cell organization including those required for the cytoskeleton, compartmentation, cell-cycle control, proteolysis, protein phosphorylation and RNA splicing. These genes may have originated with the appearance of eukaryotic life. Few similarly conserved genes that are important for multicellular organization were identified, suggesting that the transition from prokaryotes to eukaryotes required more new genes than did the transition from unicellular to multicellular organization.